Calcium oxalate crystals: an integral component of the Sclerotinia sclerotiorum/Brassica carinata pathosystem.

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Margaret B Uloth

Full Text Available Oxalic acid is an important virulence factor for disease caused by the fungal necrotrophic pathogen Sclerotinia sclerotiorum, yet calcium oxalate (CaOx crystals have not been widely reported. B. carinata stems were infected with S. sclerotiorum and observed using light microscopy. Six hours post inoculation (hpi, CaOx crystals were evident on 46% of stem sections and by 72 hpi on 100%, demonstrating that the secretion of oxalic acid by S. sclerotiorum commences before hyphal penetration. This is the first time CaOx crystals have been reported on B. carinata infected with S. sclerotiorum. The shape of crystals varied as infection progressed. Long tetragonal rods were dominant 12 hpi (68% of crystal-containing samples, but by 72 hpi, 50% of stems displayed bipyramidal crystals, and only 23% had long rods. Scanning electron microscopy from 24 hpi revealed CaOx crystals in all samples, ranging from tiny irregular crystals (< 0.5 μm to large (up to 40 μm highly organized arrangements. Crystal morphology encompassed various forms, including tetragonal prisms, oval plates, crystal sand, and druses. Large conglomerates of CaOx crystals were observed in the hyphal mass 72 hpi and these are proposed as a strategy of the fungus to hold and detoxify Ca2+ions. The range of crystal morphologies suggests that S. sclerotiorum growth and infection controls the form taken by CaOx crystals.

Mucin 4 Gene Silencing Reduces Oxidative Stress and Calcium Oxalate Crystal Formation in Renal Tubular Epithelial Cells Through the Extracellular Signal-Regulated Kinase Signaling Pathway in Nephrolithiasis Rat Model

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Ling Sun

2018-05-01

Full Text Available Background/Aims: Nephrolithiasis plagues a great number of patients all over the world. Increasing evidence shows that the extracellular signal-regulated kinase (ERK signaling pathway and renal tubular epithelial cell (RTEC dysfunction and attrition are central to the pathogenesis of kidney diseases. Mucin 4 (MUC4 is reported as an activator of ERK signaling pathway in epithelial cells. In this study, using rat models of calcium oxalate (CaOx nephrolithiasis, the present study aims to define the roles of MUC4 and ERK signaling pathway as contributors to oxidative stress and CaOx crystal formation in RTEC. Methods: Data sets of nephrolithiasis were searched using GEO database and a heat flow map was drawn. Then MUC4 function was predicted. Wistar rats were prepared for the purpose of model establishment of ethylene glycol and ammonium chloride induced CaOx nephrolithiasis. In order to assess the detailed regulatory mechanism of MUC4 silencing on the ERK signaling pathway and RTEC, we used recombinant plasmid to downregulate MUC4 expression in Wistar rat-based models. Samples from rat urine, serum and kidney tissues were reviewed to identify oxalic acid and calcium contents, BUN, Cr, Ca2+ and P3+ levels, calcium crystal formation in renal tubules and MUC4 positive expression rate. Finally, RT-qPCR, Western blot analysis, and ELISA were employed to access oxidative stress state and CaOx crystal formation in RTEC. Results: Initially, MUC4 was found to have an influence on the process of nephrolithiasis. MUC4 was upregulated in the CaOx nephrolithiasis model rats. We proved that the silencing of MUC4 triggered the inactivation of ERK signaling pathway. Following the silencing of MUC4 or the inhibition of ERK signaling pathway, the oxalic acid and calcium contents in rat urine, BUN, Cr, Ca2+ and P3+ levels in rat serum, p-ERK1/2, MCP-1 and OPN expressions in RTEC and H2O2 and MDA levels in the cultured supernatant were downregulated, but the GSH

(Dimethylphosphorylmethanaminium hydrogen oxalate–oxalic acid (2/1

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Sebastian Bialek

2014-03-01

Full Text Available The reaction of (dimethylphosphorylmethanamine (dpma with oxalic acid in ethanol yielded the title solvated salt, C3H11NOP+·C2HO4−·0.5C2H2O4. Its asymmetric unit consists of one dpmaH+ cation, one hydrogen oxalate anion and a half-molecule of oxalic acid located around a twofold rotation axis. The H atom of the hydrogen oxalate anion is statistically disordered over two positions that are trans to each other. The hydrogen oxalate monoanion is not planar (bend angle ∼16° whereas the oxalic acid molecule shows a significantly smaller bend angle (∼7°. In the crystal, the components are connected by strong O—H...O and much weaker N—H...O hydrogen bonds, leading to the formation of layers extending parallel to (001. The structure was refined from a racemically twinned crystal with twin components in an approximate 1:1 ratio.

Crystal forms of the hydrogen oxalate salt of o-desmethylvenlafaxine.

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Dichiarante, Elena; Curzi, Marco; Giaffreda, Stefano L; Grepioni, Fabrizia; Maini, Lucia; Braga, Dario

2015-06-01

To prepare new crystalline forms of the antidepressant o-desmethylvenlafaxine salt as potential new commercial forms and evaluate their physicochemical properties, in particular the dissolution rate. A new hydrogen oxalate salt of o-desmethylvenlafaxine hydrogen oxalate (ODV-OX) was synthesized, and a polymorph screening was performed using different solvents and crystallization conditions. Crystalline forms were characterized by a combination of solid-state techniques: X-ray powder diffraction, differential scanning calorimetry, thermogravimetric analysis, FT-IR spectroscopy and single crystal X-ray diffraction. The stability of all crystalline phases was tested under International Conference on Harmonisation (ICH) conditions (40°C and 75% Relative Humidity (RH)) for 1 week. Dissolution tests were performed on the hydrogen oxalate salt ODV-OX Form 1 and compared with dissolution test on the commercial form of the succinate salt of o-desmethylvenlafaxine. Five crystalline forms of ODV-OX were isolated, namely three hydrated forms (Form 1, Form 2, Form 3) and two anhydrous forms (Form 4 and Form 5). Comparative solubility tests on ODV-OX Form 1 and o-desmethylvenlafaxine succinate evidenced a significant increase in solubility for the hydrogen oxalate salt (142 g/l) with respect to the succinate salt (70 g/l). © 2015 Royal Pharmaceutical Society.

Efficient electron-induced removal of oxalate ions and formation of copper nanoparticles from copper(II oxalate precursor layers

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Kai Rückriem

2016-06-01

Full Text Available Copper(II oxalate grown on carboxy-terminated self-assembled monolayers (SAM using a step-by-step approach was used as precursor for the electron-induced synthesis of surface-supported copper nanoparticles. The precursor material was deposited by dipping the surfaces alternately in ethanolic solutions of copper(II acetate and oxalic acid with intermediate thorough rinsing steps. The deposition of copper(II oxalate and the efficient electron-induced removal of the oxalate ions was monitored by reflection absorption infrared spectroscopy (RAIRS. Helium ion microscopy (HIM reveals the formation of spherical nanoparticles with well-defined size and X-ray photoelectron spectroscopy (XPS confirms their metallic nature. Continued irradiation after depletion of oxalate does not lead to further particle growth giving evidence that nanoparticle formation is primarily controlled by the available amount of precursor.

The study of the inhibitory effect of calcium oxalate monohydrate's crystallization by two medicinal and aromatic plants: Ammi visnaga and Punica granatum.

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Kachkoul, R; Sqalli Houssaini, T; Miyah, Y; Mohim, M; El Habbani, R; Lahrichi, A

2018-03-01

Urinary lithiasis is a recurrent disease defined by the presence of calculi in the urinary tract. Most urinary calculi have as a major component calcium oxalate which occurs mainly in two crystalline forms: Calcium oxalate monohydrate (whewellite) and calcium oxalate dihydrate (weddellite). The target behind, this work is to study the inhibiting effect of the calcium oxalate's crystallization by the extract of the Ammi visnaga and the Punica granatum. The inhibition of crystallization has been studied in vitro with both the absence and the presence of the different concentrations of the extracts of the two plants. This study consists in measurement, with the UV-Visible spectrophotometer, the temporal evolution of the optical density at λ equal to 620nm corresponding to the formation of the crystals due to the mixing of metastable solutions of calcium and oxalate. The characterization of the crystals is carried out in parallel by both the Fourier transform infrared spectra (FT-IR) and the observation of the crystals with the help of an optical microscope. In this respect, the inhibition percentages were calculated from the turbidity slopes in the presence and absence of the extract. The results obtained were more effective, especially for Punica granatum with percentages of 97.8±0.12 and 83.46±1.34% against nucleation and aggregation, respectively, the order of Ammi visnaga was as follow: 73.25±0.81 and 59.44±3.3%. Thus, all correlation coefficients are greater than 0.95 and all coefficients of variation are less than 10%. The prevention and treatment of urinary lithiasis and especially in the case of recurrence by plants remains an alternative choice for medical methods. This study justified the efficacy of the plants Ammi visnaga and in particular Punica granatum against the crystallization of calcium oxalate. 3. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Role of Tamm-Horsfall protein and uromodulin in calcium oxalate crystallization

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Carvalho M.

2002-01-01

Full Text Available One of the defenses against nephrolithiasis is provided by macromolecules that modulate the nucleation, growth, aggregation and retention of crystals in the kidneys. The aim of the present study was to determine the behavior of two of these proteins, Tamm-Horsfall and uromodulin, in calcium oxalate crystallization in vitro. We studied a group of 10 male stone formers who had formed at least one kidney stone composed of calcium oxalate. They were classified as having idiopathic nephrolithiasis and had no well-known metabolic risk factors involved in kidney stone pathogenesis. Ten normal men were used as controls, as was a group consisting of five normal women and another consisting of five pregnant women. Crystallization was induced by a fixed supersaturation of calcium oxalate and measured with a Coulter Counter. All findings were confirmed by light and scanning electron microscopy. The number of particulate material deposited from patients with Tamm-Horsfall protein was higher than that of the controls (P<0.001. However, Tamm-Horsfall protein decreased the particle diameter of the stone formers when analyzed by the mode of the volume distribution curve (P<0.002 (5.64 ± 0.55 µm compared to 11.41 ± 0.48 µm of uromodulin; 15.94 ± 3.93 µm and 12.45 ± 0.97 µm of normal men Tamm-Horsfall protein and uromodulin, respectively; 8.17 ± 1.57 µm and 9.82 ± 0.95 µm of normal women Tamm-Horsfall protein and uromodulin, respectively; 12.17 ± 1.41 µm and 12.99 ± 0.51 µm of pregnant Tamm-Horsfall protein and uromodulin, respectively. Uromodulin produced fewer particles than Tamm-Horsfall protein in all groups. Nonetheless, the total volume of the crystals produced by uromodulin was higher than that produced by Tamm-Horsfall protein. Our results indicate a different effect of Tamm-Horsfall protein and uromodulin. This dual behavior suggests different functions. Tamm-Horsfall protein may act on nucleation and inhibit crystal aggregation, while

Morphological control of calcium oxalate particles in the presence of poly-(styrene-alt-maleic acid)

International Nuclear Information System (INIS)

Yu Jiaguo; Tang Hua; Cheng Bei; Zhao Xiujian

2004-01-01

Calcium oxalate (CaOx) particles exhibiting different shapes and phase structures were fabricated by a simple precipitation reaction of sodium oxalate with calcium chloride in the absence and presence of poly-(styrene-alt-maleic acid) (PSMA) as a crystal modifier at room temperature. The as-obtained products were characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of reaction conditions including pH, [Ca 2+ ]/[C 2 O 4 2- ] ratio and concentration of PSMA and CaC 2 O 4 on the crystal forms and morphologies of the as-obtained calcium oxalate were investigated. The results show that various crystal morphologies of calcium oxalate, such as parallelograms, plates, spheres, bipyramids etc. can be obtained depending on the experimental conditions. Higher polymer concentration favors formation of the metastable calcium oxalate dihydrate (COD) crystals. Lower pH is beneficial to the formation of plate-like CaOx crystals. Especially, the monodispersed parallelogram-like CaOx crystals can be produced by PSMA as an additive at pH 2. PSMA may act as a good inhibitor for urolithiasis since it induces the formation of COD and reduces the particle size of CaOx. This research may provide new insight into the morphological control of CaOx particles and the prevention of urolithiasis

Arthritis associated with calcium oxalate crystals in an anephric patient treated with peritoneal dialysis

International Nuclear Information System (INIS)

Rosenthal, A.; Ryan, L.M.; McCarty, D.J.

1988-01-01

The authors report a case of calcium oxalate arthropathy in a woman undergoing intermittent peritoneal dialysis who was not receiving pharmacologic doses of ascorbic acid. She developed acute arthritis, with calcium oxalate crystals in Heberden's and Bouchard's nodes, a phenomenon previously described in gout. Intermittent peritoneal dialysis may be less efficient than hemodialysis in clearing oxalate, and physicians should now consider calcium oxalate-associated arthritis in patients undergoing peritoneal dialysis who are not receiving large doses of ascorbic acid

Growth and study of barium oxalate single crystals in agar gel

Indian Academy of Sciences (India)

Barium oxalate was grown in agar gel at ambient temperature. The effect of various parameters like gel concentration, gel setting time and concentration of the reactants on the growth of these crystals was studied. Prismatic platy shaped spherulites and dendrites were obtained. The grown crystals were characterized by ...

Mixing state of oxalic acid containing particles in the rural area of Pearl River Delta, China: implications for the formation mechanism of oxalic acid

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C. Cheng

2017-08-01

Full Text Available The formation of oxalic acid and its mixing state in atmospheric particulate matter (PM were studied using a single-particle aerosol mass spectrometer (SPAMS in the summer and winter of 2014 in Heshan, a supersite in the rural area of the Pearl River Delta (PRD region in China. Oxalic-acid-containing particles accounted for 2.5 and 2.7 % in total detected ambient particles in summer and winter, respectively. Oxalic acid was measured in particles classified as elemental carbon (EC, organic carbon (OC, elemental and organic carbon (ECOC, biomass burning (BB, heavy metal (HM, secondary (Sec, sodium-potassium (NaK, and dust. Oxalic acid was found predominantly mixing with sulfate and nitrate during the whole sampling period, likely due to aqueous-phase reactions. In summer, oxalic-acid-containing particle number and ozone concentration followed a very similar trend, which may reflect the significant contribution of photochemical reactions to oxalic acid formation. The HM particles were the most abundant oxalic acid particles in summer and the diurnal variations in peak area of iron and oxalic acid show opposite trends, which suggests a possible loss of oxalic acid through the photolysis of iron oxalato-complexes during the strong photochemical activity period. In wintertime, carbonaceous particles contained a substantial amount of oxalic acid as well as abundant carbon clusters and BB markers. The general existence of nitric acid in oxalic-acid-containing particles indicates an acidic environment during the formation process of oxalic acid. The peak areas of nitrate, sulfate and oxalic had similar temporal change in the carbonaceous type oxalic acid particles, and the organosulfate-containing oxalic acid particles correlated well with total oxalic acid particles during the haze episode, which suggests that the formation of oxalic acid is closely associated with the oxidation of organic precursors in the aqueous phase.

The influence of freezer storage of urine samples on the BONN-Risk-Index for calcium oxalate crystallization.

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Laube, Norbert; Zimmermann, Diana J

2004-01-01

This study was performed to quantify the effect of a 1-week freezer storage of urine on its calcium oxalate crystallization risk. Calcium oxalate is the most common urinary stone material observed in urolithiasis patients in western and affluent countries. The BONN-Risk-Index of calcium oxalate crystallization risk in human urine is determined from a crystallization experiment performed on untreated native urine samples. We tested the influence of a 1-week freezing on the BONN-Risk-Index value as well as the effect of the sample freezing on the urinary osmolality. In vitro crystallization experiments in 49 native urine samples from stone-forming and non-stone forming individuals were performed in order to determine their calcium oxalate crystallization risk according to the BONN-Risk-Index approach. Comparison of the results derived from original sample investigations with those obtained from the thawed aliquots by statistical evaluation shows that i) no significant deviation from linearity between both results exists and ii) both results are identical by statistical means. This is valid for both, the BONN-Risk-Index and the osmolality data. The differences in the BONN-Risk-Index results of both procedures of BONN-Risk-Index determination, however, exceed the clinically acceptable difference. Thus, determination of the urinary calcium oxalate crystallization risk from thawed urine samples cannot be recommended.

Anti-Transforming Growth Factor β IgG Elicits a Dual Effect on Calcium Oxalate Crystallization and Progressive Nephrocalcinosis-Related Chronic Kidney Disease.

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Steiger, Stefanie; Grill, Julia Felicitas; Ma, Qiuyue; Bäuerle, Tobias; Jordan, Jutta; Smolle, Michaela; Böhland, Claudia; Lech, Maciej; Anders, Hans-Joachim

2018-01-01

Crystallopathies are a heterogeneous group of diseases caused by intrinsic or environmental microparticles or crystals, promoting tissue inflammation and scarring. Certain proteins interfere with crystal formation and growth, e.g., with intrarenal calcium oxalate (CaOx) crystal formation, a common cause of kidney stone disease or nephrocalcinosis-related chronic kidney disease (CKD). We hypothesized that immunoglobulins can modulate CaOx microcrystal formation and crystal growth and that therefore, biological IgG-based drugs designed to specifically target disease modifying proteins would elicit a dual effect on the outcome of CaOx-related crystallopathies. Indeed, both the anti-transforming growth factor (TGF)β IgG and control IgG1 antibody impaired CaOx crystallization in vitro , and decreased intrarenal CaOx crystal deposition and subsequent CKD in mice on an oxalate-rich diet compared to oxalate-fed control mice. However, the TGFβ-specific IgG antibody showed nephroprotective effects beyond those of control IgG1 and substantially reduced interstitial fibrosis as indicated by magnetic resonance imaging, silver and α-smooth muscle actin staining, RT-qPCR, and flow cytometry for pro-fibrotic macrophages. Suppressing interstitial fibrosis slowed the decline of glomerular filtration rate (GFR) compared to treatment with control IgG1 [slope of m  = -8.9 vs. m  = -14.5 μl/min/100 g body weight (BW)/day, Δ = 38.3%], an increased GFR at the end of the study (120.4 vs. 42.6 μl/min/100 g BW, Δ = 64.6%), and prolonged end stage renal disease (ESRD)-free renal survival by 10 days (Δ = 38.5%). Delayed onset of anti-TGFβ IgG from day 7 was no longer effective. Our results suggest that biological drugs can elicit dual therapeutic effects on intrinsic crystallopathies, such as anti-TGFβ IgG antibody treatment inhibits CaOx crystallization as well as interstitial fibrosis in nephrocalcinosis-related CKD.

Anti-Transforming Growth Factor β IgG Elicits a Dual Effect on Calcium Oxalate Crystallization and Progressive Nephrocalcinosis-Related Chronic Kidney Disease

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Stefanie Steiger

2018-03-01

Full Text Available Crystallopathies are a heterogeneous group of diseases caused by intrinsic or environmental microparticles or crystals, promoting tissue inflammation and scarring. Certain proteins interfere with crystal formation and growth, e.g., with intrarenal calcium oxalate (CaOx crystal formation, a common cause of kidney stone disease or nephrocalcinosis-related chronic kidney disease (CKD. We hypothesized that immunoglobulins can modulate CaOx microcrystal formation and crystal growth and that therefore, biological IgG-based drugs designed to specifically target disease modifying proteins would elicit a dual effect on the outcome of CaOx-related crystallopathies. Indeed, both the anti-transforming growth factor (TGFβ IgG and control IgG1 antibody impaired CaOx crystallization in vitro, and decreased intrarenal CaOx crystal deposition and subsequent CKD in mice on an oxalate-rich diet compared to oxalate-fed control mice. However, the TGFβ-specific IgG antibody showed nephroprotective effects beyond those of control IgG1 and substantially reduced interstitial fibrosis as indicated by magnetic resonance imaging, silver and α-smooth muscle actin staining, RT-qPCR, and flow cytometry for pro-fibrotic macrophages. Suppressing interstitial fibrosis slowed the decline of glomerular filtration rate (GFR compared to treatment with control IgG1 [slope of m = −8.9 vs. m = −14.5 μl/min/100 g body weight (BW/day, Δ = 38.3%], an increased GFR at the end of the study (120.4 vs. 42.6 μl/min/100 g BW, Δ = 64.6%, and prolonged end stage renal disease (ESRD-free renal survival by 10 days (Δ = 38.5%. Delayed onset of anti-TGFβ IgG from day 7 was no longer effective. Our results suggest that biological drugs can elicit dual therapeutic effects on intrinsic crystallopathies, such as anti-TGFβ IgG antibody treatment inhibits CaOx crystallization as well as interstitial fibrosis in nephrocalcinosis-related CKD.

Equilibrium aluminium hydroxo-oxalate phases during initial clay formation; H +-Al 3+-oxalic acid-Na + system

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Bilinski, Halka; Horvath, Laszlo; Ingri, Nils; Sjöberg, Staffan

1986-09-01

The conditions necessary for initial clay formation have been studied in different model systems comprising different organic acids besides Si and Al. In the present paper the solid phases and the precipitation boundary characterizing the subsystem H +-Al 3+-oxalic acid (H 2L) are discussed. pH and tyndallometric measurements were performed in an ionic medium of 0.6 M Na(Cl) at 25 °C. The two phases Al 3(OH) 7(C 2O 4) · 3H 2O (phase I) and NaAl(OH) 2(C 2O 4) · 3H 2O (phase II) determine the precipitation boundary. The following formation constants for the two phases were deduced: lgβ1 = lg([ Al3+] -3[ H2C2O4] -1[ H+] 9 = -21.87 ± 0.08 and lgβ11 = lg([ Al3+] -1[ H2C2O4] -1[ H+] 4 = -5.61 ± 0.06. Phase I exists in the range [ Al] tot≥ 10 -4.4moldm-3,[ H2C2O4] tot ≥ 10 -4.9moldm-3 and at pH oxalic-rich natural waters. The more soluble sodium phase is unlikely to exist in natural waters. The two phases are metastable relative to crystalline gibbsite and may be considered as the first precipitation step in the transition from aqueous Al oxalates down to stable Al hydroxide. Model calculations illustrating these competing hydrolysis-complexation reactions are discussed in terms of predominance and speciation diagrams. The solid phases have been characterized by X-ray analysis of powders, TGA and IR spectra, and tentative structures are proposed. Phase I seems to be an octahedral layer structure, in which 3/5 of the octahedral sites between two close packed oxygen sheets are occupied by Al 3+ and the oxalate ion acts as a bridge ligand between two aluminium atoms. Phase II forms a more open sheet structure and has ion exchange properties. Powder data for a phase crystallized from the studied solution after a year are also presented. This phase, Na 4Al 2(OH) 2(C 2O 4) 4 · 10H 2O, supports the results from the equilibrium analysis of recent solution data by SJöBERG and ÖHMAN (1985), who have found the dinuclear complex Al 2(OH) 2(C 2O 4) 44- to exist in a

Crystal agglomeration of europium oxalate in reaction crystallization using double-jet semi-batch reactor

International Nuclear Information System (INIS)

Kim, Woo-Sik; Kim, Woon-Soo; Kim, Kwang-Seok; Kim, Joon-Soo; Ward, Michael D.

2004-01-01

The particle agglomeration of europium oxalate was investigated in a double-jet semi-batch reactor over a wide range of operating variables, including the agitation speed, reactant feed rate, and reactant concentration. The size of the agglomerates was directly dictated by the particle collision and supersaturation promoting agglomeration and the fluid shear force inhibiting agglomeration. Thus, with a longer feeding time and higher feed concentration for the reaction crystallization, the mean particle size increased, while the corresponding total particle population decreased due to the enhanced chance of particle agglomeration, resulting from a longer residence time and higher supersaturation in the reactor. Agitation was found to exhibit a rather complicated influence on particle agglomeration. Although both particle collision and turbulent fluid shear were promoted by an increase in the mixing intensity, the crystal agglomeration of europium oxalate was maximized at around 500 rpm of agitation speed due to an optimized balance between particle aggregation and breakage

Herbal extracts of Tribulus terrestris and Bergenia ligulata inhibit growth of calcium oxalate monohydrate crystals in vitro

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Joshi, V. S.; Parekh, B. B.; Joshi, M. J.; Vaidya, A. B.

2005-02-01

A large number of people in this world are suffering from urinary stone problem. Calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) containing stones (calculi) are commonly found. In the present study, COM crystals were grown by a double diffusion gel growth technique using U-tubes. The gel was prepared from hydrated sodium metasilicate solution. The gel framework acts like a three-dimensional crucible in which the crystal nuclei are delicately held in the position of their formation, and nutrients are supplied for the growth. This technique can be utilized as a simplified screening static model to study the growth, inhibition and dissolution of urinary stones in vitro. The action of putative litholytic medicinal plants, Tribulus terrestris Linn. ( T.t) and Bergenia ligulata Linn. ( B.l.), has been studied in the growth of COM crystals. Tribulus terrestris and Bergenia ligulata are commonly used as herbal medicines for urinary calculi in India. To verify the inhibitive effect, aqueous extracts of Tribulus terrestris and Bergenia ligulata were added along with the supernatant solutions. The growth was measured and compared, with and without the aqueous extracts. Inhibition of COM crystal growth was observed in the herbal extracts. Maximum inhibition was observed in Bergenia ligulata followed by Tribulus terrestris. The results are discussed.

Study of Gel Growth Cobalt (II Oxalate Crystals as Precursor of Co3O4 Nano Particles

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Yuniar Ponco Prananto

2013-03-01

Full Text Available Crystal growth of cobalt (II oxalate in silica gel at room temperature as precursor of Co3O4 nano particles has been studied. Specifically, this project is focusing on the use of two different reaction tube types toward crystallization of cobalt (II oxalate in gel. The gel was prepared at pH 5 by reacting sodium metasilicate solution with dilute nitric acid (for U-tube and oxalic acid (for straight tube, with gelling time of 4 days and crystal growth time of 8 (for straight tube and 12 (for U-tube weeks. Result shows that pink crystalline powder was directly formed using straight tube method. The use of different solvents in straight tube method affects crystallization and could delay direct precipitation of the product. In contrast, bigger and better shape of red block crystal was yielded from U-tube method; however, longer growth time was needed. FTIR studies suggest that both growth method produces identical compound of hydrated cobalt (II oxalate. © 2013 BCREC UNDIP. All rights reservedReceived: 25th October 2012; Revised: 30th November 2012; Accepted: 5th December 2012[How to Cite: Y.P. Prananto, M.M. Khunur, D.T. Wahyuni, R.A. Shobirin, Y.R. Nata, E. Riskah, (2013. Study of Gel Growth Cobalt (II Oxalate Crystals as Precursor of Co3O4 Nano Particles. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (3: 198-204. (doi:10.9767/bcrec.7.3.4066.198-204][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.7.3.4066.198-204 ] View in  |

Kaleidoscopic Views in the Bone Marrow: Oxalate Crystals in a Patient Presenting with Bicytopenia

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Yelda Dere

2016-03-01

Full Text Available Pancytopenia associated with BM infiltration of different deposits is a rare condition mostly associated with amyloidosis or the accumulation of iron. One of the rarest deposits in the BM is oxalate crystals due to hyperoxaluria [1,2,3]. Primary hyperoxaluria, a genetic disorder due to mutation in the alanine glyoxylate aminotransferase gene, located on chromosome 2q37.3 and resulting in the conversion of glyoxylate to oxalate, is characterized by increased production of oxalic acid because of the specific liver enzyme deficiency and generally presents with renal stones, renal or liver failure, and oxalosis [4]. Calcium oxalate may even be deposited into various tissues such as those of the retina, peripheral nerves, arterial media, and heart [4,5]. The medical history of nephrolithiasis at early ages, characteristic appearance of birefringent crystals forming rosettes in the BM, and the envelope-like forms in the BM aspirates seen in our case supported the diagnosis of primary hyperoxaluria, which is best confirmed by genetic studies and treated with liver transplantation because of the location of the abnormal enzymes in the hepatocytes.

Diminution of oxalate induced renal tubular epithelial cell injury and inhibition of calcium oxalate crystallization in vitro by aqueous extract of Tribulus terrestris.

Science.gov (United States)

Aggarwal, A; Tandon, S; Singla, S K; Tandon, C

2010-01-01

Recurrence and persistent side effects of present day treatment for urolithiasis restrict their use, so an alternate solution, using phytotherapy is being sought. The present study attempted to evaluate the antilithiatic properties of Tribulus terrestris commonly called as "gokhru" which is often used in ayurveda to treat various urinary diseases including urolithiasis. The activity of Tribulus terrestris was investigated on nucleation and the growth of the calcium oxalate (CaOx) crystals as well as on oxalate induced cell injury of NRK 52E renal epithelial cells. Tribulus terrestris extract exhibited a concentration dependent inhibition of nucleation and the growth of CaOx crystals. When NRK-52E cells were injured by exposure to oxalate for 72 h, Tribulus terrestris extract prevented the injury in a dose-dependent manner. On treatment with the different concentrations of the plant, the cell viability increased and lactate dehydrogenase release decreased in a concentration dependent manner. The current data suggests that Tribulus terrestris extract not only has a potential to inhibit nucleation and the growth of the CaOx crystals but also has a cytoprotective role. Our results indicate that it could be a potential candidate for phytotherapy against urolithiasis.

Kinetic study of nucleation and crystal growth during oxalic precipitation in the nuclear industry

International Nuclear Information System (INIS)

Andrieu, Murielle

1999-01-01

In spite of an extensive use in chemical industry, most of precipitation processes are based on global and empirical knowledge. However, in the recent years, fundamental and phenomenological theories have been developed and they can be used to better understand the mechanisms of precipitation of plutonium IV oxalate, which is a significant stage of the irradiated fuel reprocessing. For this reason, appropriate methods were developed to study nucleation and crystal growth kinetics in a nuclear environment under a wide range of operating conditions. Each phenomena was studied individually in order to reduce the free parameters of the System. This study bears on the oxalates of plutonium and elements which simulate plutonium behaviour during the precipitation, neodymium III and uranium IV. A compact apparatus of a specific construction was used for nucleation measurements in accordance with the Nielsen's method. The state of the mixing was characterised at the reactor scale (macro-mixing) and at molecular scale (micro-mixing). The experimental results for the studied oxalates are in good agreement with the Volmer and Weber's theory. We propose primary nucleation kinetic laws over a wide range of operating conditions (temperature, non-stoichiometric conditions, acidity...). An original method, using a high seed charge, was developed for the determination of crystal growth kinetics, in a batch crystallizer. The crystal growth rate is first order with respect to the supersaturation and the kinetic constant follows an Arrhenius type relation with activation energies of 14, 29 and 36 kJ.mol -1 for respectively neodymium III, uranium IV and plutonium IV oxalates. The overall growth process is surface integration controlled, with a screw dislocation mechanism. [fr

Hydrothermal growth of cross-linked hyperbranched copper dendrites using copper oxalate complex

Science.gov (United States)

Truong, Quang Duc; Kakihana, Masato

2012-06-01

A facile and surfactant-free approach has been developed for the synthesis of cross-linked hyperbranched copper dendrites using copper oxalate complex as a precursor and oxalic acid as a reducing and structure-directing agent. The synthesized particles are composed of highly branched nanostructures with unusual cross-linked hierarchical networks. The formation of copper dendrites can be explained in view of both diffusion control and aggregation-based growth model accompanied by the chelation-assisted assembly. Oxalic acid was found to play dual roles as reducing and structure-directing agent based on the investigation results. The understanding on the crystal growth and the roles of oxalic acid provides clear insight into the formation mechanism of hyperbranched metal dendrites.

Diminution of oxalate induced renal tubular epithelial cell injury and inhibition of calcium oxalate crystallization in vitro by aqueous extract of Tribulus terrestris

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A. Aggarwal

2010-08-01

Full Text Available PURPOSE: Recurrence and persistent side effects of present day treatment for urolithiasis restrict their use, so an alternate solution, using phytotherapy is being sought. The present study attempted to evaluate the antilithiatic properties of Tribulus terrestris commonly called as “gokhru” which is often used in ayurveda to treat various urinary diseases including urolithiasis. MATERIALS AND METHODS: The activity of Tribulus terrestris was investigated on nucleation and the growth of the calcium oxalate (CaOx crystals as well as on oxalate induced cell injury of NRK 52E renal epithelial cells. RESULTS: Tribulus terrestris extract exhibited a concentration dependent inhibition of nucleation and the growth of CaOx crystals. When NRK-52E cells were injured by exposure to oxalate for 72 h, Tribulus terrestris extract prevented the injury in a dose-dependent manner. On treatment with the different concentrations of the plant, the cell viability increased and lactate dehydrogenase release decreased in a concentration dependent manner. CONCLUSION: The current data suggests that Tribulus terrestris extract not only has a potential to inhibit nucleation and the growth of the CaOx crystals but also has a cytoprotective role. Our results indicate that it could be a potential candidate for phytotherapy against urolithiasis.

Pathology and Epidemiology of Oxalate Nephrosis in Cheetahs.

Science.gov (United States)

Mitchell, Emily P; Church, Molly E; Nemser, Sarah M; Yakes, Betsy Jean; Evans, Eric R; Reimschuessel, Renate; Lemberger, Karin; Thompson, Peter N; Terio, Karen A

2017-11-01

To investigate cases of acute oxalate nephrosis without evidence of ethylene glycol exposure, archived data and tissues from cheetahs ( Acinonyx jubatus) from North America ( n = 297), southern Africa ( n = 257), and France ( n = 40) were evaluated. Renal and gastrointestinal tract lesions were characterized in a subset of animals with ( n = 100) and without ( n = 165) oxalate crystals at death. Crystals were confirmed as calcium oxalate by Raman spectroscopy in 45 of 47 cheetahs tested. Crystals were present in cheetahs from 3.7 months to 15.9 years old. Cheetahs younger than 1.5 years were less likely to have oxalates than older cheetahs ( P = .034), but young cheetahs with oxalates had more oxalate crystals than older cheetahs ( P Cheetahs with oxalate crystals were more likely to have renal amyloidosis, interstitial nephritis, or colitis and less likely to have glomerular loop thickening or gastritis than those without oxalates. Crystal number was positively associated with renal tubular necrosis ( P ≤ .001), regeneration ( P = .015), and casts ( P ≤ .001) but inversely associated with glomerulosclerosis, renal amyloidosis, and interstitial nephritis. Crystal number was unrelated to the presence or absence of colitis and was lower in southern African than American and European animals ( P = .01). This study found no evidence that coexisting chronic renal disease (amyloidosis, interstitial nephritis, or glomerulosclerosis), veno-occlusive disease, gastritis, or enterocolitis contributed significantly to oxalate nephrosis. Oxalate-related renal disease should be considered as a potential cause of acute renal failure, especially in young captive cheetahs. The role of location, diet, stress, and genetic predisposition in the pathogenesis of oxalate nephrosis in cheetahs warrants further study.

Reevaluation of the plant "gemstones": Calcium oxalate crystals sustain photosynthesis under drought conditions.

Science.gov (United States)

Tooulakou, Georgia; Giannopoulos, Andreas; Nikolopoulos, Dimosthenis; Bresta, Panagiota; Dotsika, Elissavet; Orkoula, Malvina G; Kontoyannis, Christos G; Fasseas, Costas; Liakopoulos, Georgios; Klapa, Maria I; Karabourniotis, George

2016-09-01

Land plants face the perpetual dilemma of using atmospheric carbon dioxide for photosynthesis and losing water vapors, or saving water and reducing photosynthesis and thus growth. The reason behind this dilemma is that this simultaneous exchange of gases is accomplished through the same minute pores on leaf surfaces, called stomata. In a recent study we provided evidence that pigweed, an aggressive weed, attenuates this problem exploiting large crystals of calcium oxalate as dynamic carbon pools. This plant is able to photosynthesize even under drought conditions, when stomata are closed and water losses are limited, using carbon dioxide from crystal decomposition instead from the atmosphere. Abscisic acid, an alarm signal that causes stomatal closure seems to be implicated in this function and for this reason we named this path "alarm photosynthesis." The so-far "enigmatic," but highly conserved and widespread among plant species calcium oxalate crystals seem to play a crucial role in the survival of plants.

Efficient green luminescence of terbium oxalate crystals: A case study with Judd-Ofelt theory and single crystal structure analysis and the effect of dehydration on luminescence

Science.gov (United States)

Alexander, Dinu; Joy, Monu; Thomas, Kukku; Sisira, S.; Biju, P. R.; Unnikrishnan, N. V.; Sudarsanakumar, C.; Ittyachen, M. A.; Joseph, Cyriac

2018-06-01

Design and synthesis of Lanthanide based metal organic framework is a frontier area of research owing to their structural diversity enabling specific applications. The luminescence properties of rare earths, tuned by the structural features of Ln-MOFs are investigated extensively. Rare earth oxalates which can be synthesized in a facile method, ensuring the structural features of MOFs with excellent photoluminescence characteristics deserves much attention. This work is the first time report on the single crystal structure and Judd-Ofelt (JO) theoretical analysis - their correlation with the intense and sharp green luminescence of Terbium oxalate crystals. The intense green luminescence observed for Terbium oxalate crystals for a wide range of excitation from DUV to visible region despite the luminescence limiting factors are discussed. The absence of concentration quenching and lifting up of forbidden nature of f-f transitions, allowing direct excitation of Terbium ions is analysed with the help of JO theory and single crystal structure analysis. The JO analysis predicted the asymmetry of Terbium sites, allowing the electric dipole transitions and from the JO intensity parameters, promising spectroscopic parameters - emission cross section, branching ratio, gain band width and gain coefficient of the material were calculated. The single crystal structure analysis revealed the asymmetry of Tb sites and structure of Terbium oxalate is formed by the hydrogen bonded stacking of overlapped six Terbium membered rings connected by the oxalate ligands. The molecularly thick layers thus formed on the crystal surface are imaged by the atomic force microscopy. The presence of water channels in the structure and the effect of lattice water molecules on the luminescence intensity are also investigated.

Crystal structure of dimethylammonium hydrogen oxalate hemi(oxalic acid

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Waly Diallo

2015-05-01

Full Text Available Single crystals of the title salt, Me2NH2+·HC2O4−·0.5H2C2O4, were isolated as a side product from the reaction involving Me2NH, H2C2O4 and Sn(n-Bu3Cl in a 1:2 ratio in methanol or by the reaction of the (Me2NH22C2O4 salt and Sn(CH33Cl in a 2:1 ratio in ethanol. The asymmetric unit comprises a dimethylammonium cation (Me2NH2+, an hydrogenoxalate anion (HC2O4−, and half a molecule of oxalic acid (H2C2O4 situated about an inversion center. From a supramolecular point of view, the three components interact together via hydrogen bonding. The Me2NH2+ cations and the HC2O4− anions are in close proximity through bifurcated N—H...(O,O hydrogen bonds, while the HC2O4− anions are organized into infinite chains via O—H...O hydrogen bonds, propagating along the a-axis direction. In addition, the oxalic acid (H2C2O4 molecules play the role of connectors between these chains. Both the carbonyl and hydroxyl groups of each diacid are involved in four intermolecular interactions with two Me2NH2+ and two HC2O4− ions of four distinct polymeric chains, via two N—H...O and two O—H...O hydrogen bonds, respectively. The resulting molecular assembly can be viewed as a two-dimensional bilayer-like arrangement lying parallel to (010, and reinforced by a C—H...O hydrogen bond.

Crystal structure of di?methyl?ammonium hydrogen oxalate hemi(oxalic acid)

OpenAIRE

Diallo, Waly; Gueye, Ndongo; Crochet, Aur?lien; Plasseraud, Laurent; Cattey, H?l?ne

2015-01-01

Single crystals of the title salt, Me2NH2 +?HC2O4 ??0.5H2C2O4, were isolated as a side product from the reaction involving Me2NH, H2C2O4 and Sn(n-Bu)3Cl in a 1:2 ratio in methanol or by the reaction of the (Me2NH2)2C2O4 salt and Sn(CH3)3Cl in a 2:1 ratio in ethanol. The asymmetric unit comprises a di?methyl?ammonium cation (Me2NH2 +), an hydrogenoxalate anion (HC2O4 ?), and half a mol?ecule of oxalic acid (H2C2O4) situated about an inversion center. From a supra?molecular point of view, the t...

The crystal structure of paramagnetic copper(ii) oxalate (CuC2O4):

DEFF Research Database (Denmark)

Christensen, Axel Nørlund; Lebech, Bente; Andersen, Niels Hessel

2014-01-01

Synthetic copper(ii) oxalate, CuC2O4, was obtained in a precipitation reaction between a copper(ii) solution and an aqueous solution of oxalic acid. The product was identified from its conventional X-ray powder patterns which match that of the copper mineral Moolooite reported to have...... the composition CuC2O4·0.44H2O. Time resolved in situ investigations of the thermal decomposition of copper(ii) oxalate using synchrotron X-ray powder diffraction showed that in air the compound converts to Cu2O at 215 °C and oxidizes to CuO at 345 °C. Thermo gravimetric analysis performed in an inert Ar....... The crystal structure consists of a random stacking of CuC2O4 micro-crystallites where half the Cu-atoms are placed at (2a) and the other half at (2b) positions with the corresponding oxalate molecules centred around the corresponding (2b) and (2a) site positions, respectively. The diffraction patterns...

(Di­methyl­phosphor­yl)methanaminium hydrogen oxalate–oxalic acid (2/1)

Science.gov (United States)

Bialek, Sebastian; Clemens, Rebecca; Reiss, Guido J.

2014-01-01

The reaction of (di­methyl­phosphor­yl)methanamine (dpma) with oxalic acid in ethanol yielded the title solvated salt, C3H11NOP+·C2HO4 −·0.5C2H2O4. Its asymmetric unit consists of one dpmaH+ cation, one hydrogen oxalate anion and a half-mol­ecule of oxalic acid located around a twofold rotation axis. The H atom of the hydrogen oxalate anion is statistically disordered over two positions that are trans to each other. The hydrogen oxalate monoanion is not planar (bend angle ∼16°) whereas the oxalic acid molecule shows a significantly smaller bend angle (∼7°). In the crystal, the components are connected by strong O—H⋯O and much weaker N—H⋯O hydrogen bonds, leading to the formation of layers extending parallel to (001). The structure was refined from a racemically twinned crystal with twin components in an approximate 1:1 ratio. PMID:24765013

Reevaluation of the plant “gemstones”: Calcium oxalate crystals sustain photosynthesis under drought conditions

Science.gov (United States)

Tooulakou, Georgia; Giannopoulos, Andreas; Nikolopoulos, Dimosthenis; Bresta, Panagiota; Dotsika, Elissavet; Orkoula, Malvina G.; Kontoyannis, Christos G.; Fasseas, Costas; Liakopoulos, Georgios; Klapa, Maria I.; Karabourniotis, George

2016-01-01

ABSTRACT Land plants face the perpetual dilemma of using atmospheric carbon dioxide for photosynthesis and losing water vapors, or saving water and reducing photosynthesis and thus growth. The reason behind this dilemma is that this simultaneous exchange of gases is accomplished through the same minute pores on leaf surfaces, called stomata. In a recent study we provided evidence that pigweed, an aggressive weed, attenuates this problem exploiting large crystals of calcium oxalate as dynamic carbon pools. This plant is able to photosynthesize even under drought conditions, when stomata are closed and water losses are limited, using carbon dioxide from crystal decomposition instead from the atmosphere. Abscisic acid, an alarm signal that causes stomatal closure seems to be implicated in this function and for this reason we named this path “alarm photosynthesis.” The so-far “enigmatic,” but highly conserved and widespread among plant species calcium oxalate crystals seem to play a crucial role in the survival of plants. PMID:27471886

Growth and characterization of strontium oxalate crystals by the decomposition of ascorbic acid in presence of strontium chloride

International Nuclear Information System (INIS)

Bijini, B.R.; Prasanna, S.; Rajendra Babu, K.; Deepa, M.

2010-01-01

Full text: Ascorbic acid (vitamin c) is an important organic compound that helps to maintain the optimal health of human body. It is essential for the development and maintenance of connective tissues. Vitamin C plays an important role in a number of metabolic functions including the activation of the B vitamin, folic acid, the conversion of cholesterol to bile acids and the conversion of the amino acid, tryptophan, to the neurotransmitter, serotonin. During the process of metabolism it decomposes into oxalic acid. This compound is photosensitive and has least thermal stability. The decomposition of Ascorbic acid has been studied in various conditions. It is reported that decomposition of ascorbic acid in presence of Cd 2+ ions leads to the formation of cadmium oxalate crystals. In the present work, in presence of Sr 2+ ion the ascorbic acid is decomposed to Strontium Oxalate in gel media. In this technique, silica gel is used as a medium to grow crystals. Slow diffusion of reactants in the gel medium can be considered to mimic the growth of crystals in the human body. Gels were prepared by mixing appropriate quantities of sodium meta silicate and ascorbic acid, adjusting the pH in the range 5-7.5. Over the set gel, the feed solution of 1M Strontium chloride was added. Yellowish prismatic and bar shaped crystals were obtained within 24 hours. The nucleation density is maximum at a pH of 6 and minimum at 5. Good quality crystals were obtained for a pH of 5 and gel density 1.05g/cc. The FTIR spectra of grown crystals are recorded and analyzed.The band at 3431 cm -1 is assigned to OH stretching frequency of co-ordinated water molecule and the band at 1637cm -1 corresponds to C=O Stretching of carbonyl group. The band at 1319cm -1 is assigned to symmetric stretching of COO- group. The IR band at 767cm -1 corresponds to the combined effect of inplane deformation of CO 2 and the presence of metal oxygen bond .The band at 505cm -1 is due to wagging mode

Preventive treatment of calcium oxalate crystal deposition with immortal flowers.

Science.gov (United States)

Orhan, Nilüfer; Onaran, Metin; Şen, İlker; Işık Gönül, İpek; Aslan, Mustafa

2015-04-02

A number of medicinal plants are used for their diuretic, urolithiatic and anti-inflammatory effects on urinary system problems in Turkey and the most common traditional remedy for kidney stones is the tea of immortal flowers. The aim of this study is to evaluate the preventive effect of infusions prepared from capitulums of Helichrysum graveolens (M.Bieb.) Sweet (HG) and Helichrysum stoechas ssp. barellieri (Ten.) Nyman (HS) on formation of kidney stones. Sodium oxalate (Ox-70mg/kg intraperitoneally) was used to induce kidney stones on Wistar albino rats. At the same time, two different doses of the plant extracts (HG: 62.5 and 125mg/kg; HS: 78 and 156mg/kg) were dissolved in the drinking water and administered to animals for 5 days. Potassium citrate was used as positive control in the experiments. During the experiment, water intake, urine volume and body weights of the animals were recorded. At the end of the experiments, liver, kidney and body weights of the animals were determined; biochemical analysis were conducted on urine, blood and plasma samples. Histopathological changes in kidney tissues were examined and statistical analysis were evaluated. HS extract showed the highest preventive effect at 156mg/kg dose (stone formation score: 1.16), whereas a number of kidney stones were maximum in sodium oxalate group (stone formation score: 2.66). Helichrysum extracts decreased urine oxalate and uric acid levels and increased citrate levels significantly. In addition, Helichrysum extracts regulated the negative changes in biochemical and hematological parameters occurred after Ox injection. We conclude that Helichrysum extracts could reduce the formation and growth of kidney stones in Ox-induced urolithiasis and can be beneficial for patients with recurrent stones. In addition, this is the first study on the preventive effect of immortal flowers. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Evaluation of oxalate decarboxylase and oxalate oxidase for industrial applications.

Science.gov (United States)

Cassland, Pierre; Sjöde, Anders; Winestrand, Sandra; Jönsson, Leif J; Nilvebrant, Nils-Olof

2010-05-01

Increased recirculation of process water has given rise to problems with formation of calcium oxalate incrusts (scaling) in the pulp and paper industry and in forest biorefineries. The potential in using oxalate decarboxylase from Aspergillus niger for oxalic acid removal in industrial bleaching plant filtrates containing oxalic acid was examined and compared with barley oxalate oxidase. Ten different filtrates from chemical pulping were selected for the evaluation. Oxalate decarboxylase degraded oxalic acid faster than oxalate oxidase in eight of the filtrates, while oxalate oxidase performed better in one filtrate. One of the filtrates inhibited both enzymes. The potential inhibitory effect of selected compounds on the enzymatic activity was tested. Oxalate decarboxylase was more sensitive than oxalate oxidase to hydrogen peroxide. Oxalate decarboxylase was not as sensitive to chlorate and chlorite as oxalate oxidase. Up to 4 mM chlorate ions, the highest concentration tested, had no inhibitory effect on oxalate decarboxylase. Analysis of the filtrates suggests that high concentrations of chlorate present in some of the filtrates were responsible for the higher sensitivity of oxalate oxidase in these filtrates. Oxalate decarboxylase was thus a better choice than oxalate oxidase for treatment of filtrates from chlorine dioxide bleaching.

Crystal structure of 2-methyl-1H-imidazol-3-ium hydrogen oxalate dihydrate

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Mouhamadou Birame Diop

2016-08-01

Full Text Available Single crystals of the title molecular salt, C4H7N2+·HC2O4−·2H2O, were isolated from the reaction of 2-methyl-1H-imidazole and oxalic acid in a 1:1 molar ratio in water. In the crystal, the cations and anions are positioned alternately along an infinite [010] ribbon and linked together through bifurcated N—H...(O,O hydrogen bonds. The water molecules of crystallization link the chains into (10-1 bilayers, with the methyl groups of the cations organized in an isotactic manner.

Studying inhibition of calcium oxalate stone formation: an in vitro approach for screening hydrogen sulfide and its metabolites

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S. Vaitheeswari

2015-06-01

Full Text Available ABSTRACTPurpose:Calcium oxalate urolithiasis is one of the most common urinary tract diseases and is of high prevalence. The present study proposes to evaluate the antilithiatic property of hydrogen sulfide and its metabolites like thiosulfate & sulfate in an in vitro model.Materials and Methods:The antilithiatic activity of sodium hydrogen sulfide (NaSH, sodium thiosulfate (Na2S2O3 and sodium sulfate (Na2SO4 on the kinetics of calcium oxalate crystal formation was investigated both in physiological buffer and in urine from normal and recurrent stone forming volunteers. The stones were characterized by optical and spectroscopic techniques.Results:The stones were characterized to be monoclinic, prismatic and bipyramidal habit which is of calcium monohydrate and dihydrate nature. The FTIR displayed fingerprint corresponding to calcium oxalate in the control while in NaSH treated, S=O vibrations were visible in the spectrum. The order of percentage inhibition was NaSH>Na2S2O3>Na2SO4.Conclusion:Our study indicates that sodium hydrogen sulfide and its metabolite thiosulfate are inhibitors of calcium oxalate stone agglomeration which makes them unstable both in physiological buffer and in urine. This effect is attributed to pH changes and complexing of calcium by S2O32-and SO42- moiety produced by the test compounds.

Neptunium (IV) oxalate solubility

International Nuclear Information System (INIS)

Luerkens, D.W.

1983-07-01

The equilibrium solubility of neptunium (IV) oxalate in nitric/oxalic acid solutions was determined at 22 0 C, 45 0 C, and 60 0 C. The concentrations of nitric/oxalic acid solutions represented a wide range of free oxalate ion concentration. A mathematical solubility model was developed which is based on the formation of the known complexes of neptunium (IV) oxalate. the solubility model uses a simplified concentration parameter which is proportional to the free oxalate ion concentration. The solubility model can be used to estimate the equilibrium solubility of neptunium (IV) oxalate over a wide range of oxalic and nitric acid concentrations at each temperature

Acute oxalate nephropathy caused by ethylene glycol poisoning

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Jung Woong Seo

2012-12-01

Full Text Available Ethylene glycol (EG is a sweet-tasting, odorless organic solvent found in many agents, such as anti-freeze. EG is composed of four organic acids: glycoaldehyde, glycolic acid, glyoxylic acid and oxalic acid in vivo. These metabolites are cellular toxins that can cause cardio-pulmonary failure, life-threatening metabolic acidosis, central nervous system depression, and kidney injury. Oxalic acid is the end product of EG, which can precipitate to crystals of calcium oxalate monohydrate in the tubular lumen and has been linked to acute kidney injury. We report a case of EG-induced oxalate nephropathy, with the diagnosis confirmed by kidney biopsy, which showed acute tubular injury of the kidneys with extensive intracellular and intraluminal calcium oxalate monohydrate crystal depositions.

Estimation of the oxalate content of foods and daily oxalate intake

Science.gov (United States)

Holmes, R. P.; Kennedy, M.

2000-01-01

BACKGROUND: The amount of oxalate ingested may be an important risk factor in the development of idiopathic calcium oxalate nephrolithiasis. Reliable food tables listing the oxalate content of foods are currently not available. The aim of this research was to develop an accurate and reliable method to measure the food content of oxalate. METHODS: Capillary electrophoresis (CE) and ion chromatography (IC) were compared as direct techniques for the estimation of the oxalate content of foods. Foods were thoroughly homogenized in acid, heat extracted, and clarified by centrifugation and filtration before dilution in water for analysis. Five individuals consuming self-selected diets maintained food records for three days to determine their mean daily oxalate intakes. RESULTS: Both techniques were capable of adequately measuring the oxalate in foods with a significant oxalate content. With foods of very low oxalate content (choice over IC for estimating the oxalate content of foods with a medium (>10 mg/100 g) to high oxalate content due to a faster analysis time and lower running costs, whereas IC may be better suited for the analysis of foods with a low oxalate content. Accurate estimates of the oxalate content of foods should permit the role of dietary oxalate in urinary oxalate excretion and stone formation to be clarified. Other factors, apart from the amount of oxalate ingested, appear to exert a major influence over the amount of oxalate excreted in the urine.

SYNTHESIS, THERMAL STUDIES AND CRYSTAL STRUCTURE OF 4-AMINOPYRIDINIUM SEMI-OXALATE HEMIHYDRATE

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CECILIA CHACÓN

2017-06-01

Full Text Available The title compound has been synthesized by grinding in an agate mortar. Its structure was characterized by TGA-DSC studies and single-crystal X-ray diffraction. This compound crystallize in the monoclinic system with space group C2/c, Z = 4, and unit cell parameters a = 16.109(2 Å, b = 5.748(7 Å, c = 20.580(3 Å, β = 107.36(1°. The salt, C2HO4-.C5H7N+.0.5 H2O, is an ionic ensemble assisted by hydrogen bonds established between 4-aminopyridinium cations, oxalate anions and water molecules. The three components thus construct a supramolecular assembly with a three-dimensional hydrogen bonded framework.

Protection of metal artefacts with the formation of metal-oxalates complexes by Beauveria bassiana.

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Edith eJoseph

2012-01-01

Full Text Available Several fungi present high tolerance to toxic metals and some are able to transform metals into metal-oxalate complexes. In this study, the ability of Beauveria bassiana to produce copper oxalates was evaluated in vitro. Growth performance was tested on various copper-containing media. B. bassiana proved highly resistant to copper, tolerating concentrations of up to 20 g.L-1, and precipitating copper oxalates on all media tested. Chromatographic analyses showed that this species produced oxalic acid as sole metal chelator. The production of metal-oxalates can be used in the restoration and conservation of archaeological and modern metal artefacts. The production of copper-oxalates was confirmed directly using metallic pieces (both archaeological and modern. The conversion of corrosion products into copper oxalates was demonstrated as well. In order to assess whether the capability of B. bassiana to produce metal-oxalates could be applied to other metals, iron and silver were tested as well. Iron appears to be directly sequestered in the wall of the fungal hyphae forming oxalates and probably goethite. However, the formation of a homogeneous layer on the object is not yet optimal. Silver nitrate was extracellularly reduced into nanoparticles of elemental silver by an unknown mechanism. The production of copper oxalates is immediately applicable for the conservation of copper-based artefacts. For iron and silver this is not yet the case. However, the vast ability of B. bassiana to transform toxic metals using different immobilization mechanisms seems to offer considerable possibilities for industrial applications, such as the bioremediation of contaminated soils or the green synthesis of chemicals.

Spectroscopic properties of Pr -doped erbium oxalate crystals

Indian Academy of Sciences (India)

Spectroscopic properties of praseodymium ions-doped erbium oxalate ... solution with specific gravity 1.04 g/cm3 was mixed homogeneously with 0.5 M oxalic ... of concentrated nitric acid were transferred carefully and gently through the wall ...

Two New Families of Lanthanide Mixed-Ligand Complexes, Oxalate-Carbonate and Oxalate-Formate: Synthesis and Structure of [Ce(H 2O)] 2(C 2O 4) 2(CO 3)·2.5 H 2O and Ce(C 2O 4)(HCO 2)

Science.gov (United States)

Romero, S.; Mosset, A.; Trombe, J. C.

1996-12-01

Two new families of lanthanide complexes associating the ligands oxalate and carbonate or oxalate and formate have been prepared under autogenous pressure at 200°C using a pseudo-hydrothermal method. The two families have been extended to some lanthanides ( Ln): oxalate-carbonate Ln= Ce, Pr, Nd, and Eu; oxalate-formate Ln= La, Ce, and Sm. The starting suspension contains either oxalate or a mixture of oxalate and oxalic acid. The structures have been solved for the element cerium. In both cases, the structure is built up from cerium atoms sharing all their oxygen atoms with oxalate and carbonate or oxalate and formate ligands, thus forming a three-dimensional network. The cerium polyhedra share either faces or edges or corners. The coordination scheme of the oxalate ligands is variable: bischelating, bischelating and monodentate, or bischelating and bismonodentate. The carbonate group acts as a bischelating and bismonodentate ligand while the formate group is chelating and monodentate. The characterization of these two original families by infrared spectra and thermal behavior is presented for some pure phases. A tentative explanation of the synthesis of these two phases will be emphasized.

Crystal structure of di­methyl­ammonium hydrogen oxalate hemi(oxalic acid)

Science.gov (United States)

Diallo, Waly; Gueye, Ndongo; Crochet, Aurélien; Plasseraud, Laurent; Cattey, Hélène

2015-01-01

Single crystals of the title salt, Me2NH2 +·HC2O4 −·0.5H2C2O4, were isolated as a side product from the reaction involving Me2NH, H2C2O4 and Sn(n-Bu)3Cl in a 1:2 ratio in methanol or by the reaction of the (Me2NH2)2C2O4 salt and Sn(CH3)3Cl in a 2:1 ratio in ethanol. The asymmetric unit comprises a di­methyl­ammonium cation (Me2NH2 +), an hydrogenoxalate anion (HC2O4 −), and half a mol­ecule of oxalic acid (H2C2O4) situated about an inversion center. From a supra­molecular point of view, the three components inter­act together via hydrogen bonding. The Me2NH2 + cations and the HC2O4 − anions are in close proximity through bifurcated N—H⋯(O,O) hydrogen bonds, while the HC2O4 − anions are organized into infinite chains via O—H⋯O hydrogen bonds, propagating along the a-axis direction. In addition, the oxalic acid (H2C2O4) mol­ecules play the role of connectors between these chains. Both the carbonyl and hydroxyl groups of each diacid are involved in four inter­molecular inter­actions with two Me2NH2 + and two HC2O4 − ions of four distinct polymeric chains, via two N—H⋯O and two O—H⋯O hydrogen bonds, respectively. The resulting mol­ecular assembly can be viewed as a two-dimensional bilayer-like arrangement lying parallel to (010), and reinforced by a C—H⋯O hydrogen bond. PMID:25995858

Mimicking the biomolecular control of calcium oxalate monohydrate crystal growth: effect of contiguous glutamic acids.

Science.gov (United States)

Grohe, Bernd; Hug, Susanna; Langdon, Aaron; Jalkanen, Jari; Rogers, Kem A; Goldberg, Harvey A; Karttunen, Mikko; Hunter, Graeme K

2012-08-21

Scanning confocal interference microscopy (SCIM) and molecular dynamics (MD) simulations were used to investigate the adsorption of the synthetic polypeptide poly(l-glutamic acid) (poly-glu) to calcium oxalate monohydrate (COM) crystals and its effect on COM formation. At low concentrations (1 μg/mL), poly-glu inhibits growth most effectively in ⟨001⟩ directions, indicating strong interactions of the polypeptide with {121} crystal faces. Growth in directions was inhibited only marginally by 1 μg/mL poly-glu, while growth in directions did not appear to be affected. This suggests that, at low concentrations, poly-glu inhibits lattice-ion addition to the faces of COM in the order {121} > {010} ≥ {100}. At high concentrations (6 μg/mL), poly-glu resulted in the formation of dumbbell-shaped crystals featuring concave troughs on the {100} faces. The effects on crystal growth indicate that, at high concentrations, poly-glu interacts with the faces of COM in the order {100} > {121} > {010}. This mirrors MD simulations, which predicted that poly-glu will adsorb to a {100} terrace plane (most calcium-rich) in preference to a {121} (oblique) riser plane but will adsorb to {121} riser plane in preference to an {010} terrace plane (least calcium-rich). The effects of different poly-glu concentration on COM growth (1-6 μg/mL) may be due to variations between the faces in terms of growth mechanism and/or (nano)roughness, which can affect surface energy. In addition, 1 μg/mL might not be adequate to reach the critical concentration for poly-glu to significantly pin step movement on {100} and {010} faces. Understanding the mechanisms involved in these processes is essential for the development of agents to reduce recurrence of kidney stone disease.

Calcium oxalate stone and gout.

Science.gov (United States)

Marickar, Y M Fazil

2009-12-01

Gout is well known to be produced by increased uric acid level in blood. The objective of this paper is to assess the relationship between gout and calcium oxalate stone formation in the humans. 48 patients with combination of gout and calcium oxalate stone problem were included. The biochemical values of this group were compared with 38 randomly selected uric acid stone patients with gout, 43 stone patients with gout alone, 100 calcium oxalate stone patients without gout and 30 controls, making a total of 259 patients. Various biochemical parameters, namely serum calcium, phosphorus and uric acid and 24-h urine calcium, phosphorus, uric acid, oxalate, citrate and magnesium were analysed. ANOVA and Duncan's multiple-range tests were performed to assess statistical significance of the variations. The promoters of stone formation, namely serum calcium (P stone patients and gouty calcium oxalate stone patients compared to the non-gouty patients and controls. Urine oxalate (P stones patients. The inhibitor urine citrate (P stone gouty patients, followed by the gouty uric acid stone formers and gouty calcium oxalate stone patients. The high values of promoters, namely uric acid and calcium in the gouty stone patients indicate the tendency for urinary stone formation in the gouty stone patients. There is probably a correlation between gout and calcium oxalate urinary stone. We presume this mechanism is achieved through the uric acid metabolism. The findings point to the summation effect of metabolic changes in development of stone disease.

Plasma biochemistry and urinalysis variables of koalas (Phascolarctos cinereus) with and without oxalate nephrosis.

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Speight, K Natasha; Haynes, Julie I; Boardman, Wayne; Breed, William G; Taggart, David A; Rich, Brian; Woolford, Lucy

2014-06-01

Oxalate nephrosis is a highly prevalent disease in the Mount Lofty Ranges koala population in South Australia, but associated clinicopathologic findings remain undescribed. The aims of this study were to determine plasma biochemical and urinalysis variables, particularly for renal function and urinary crystal morphology and composition, in koalas with oxalate nephrosis. Blood and urine samples from Mount Lofty Ranges koalas with oxalate nephrosis were compared with those unaffected by renal oxalate crystal deposition from Mount Lofty and Kangaroo Island, South Australia and Moggill, Queensland. Plasma and urine biochemistry variables were analyzed using a Cobas Bio analyzer, and urinary oxalate by high-performance liquid chromatography. Urinary crystal composition was determined by infrared spectroscopy and energy dispersive X-ray analysis. Azotemia (urea > 6.6 mmol/L, creatinine > 150 μmol/L) was found in 93% of koalas with oxalate nephrosis (n = 15). All azotemic animals had renal insufficiency (urine specific gravity [USG] < 1.035), and in 83%, USG was < 1.030. Koalas with oxalate nephrosis were hyperoxaluric compared with Queensland koalas (P < .01). Urinary crystals from koalas with oxalate nephrosis had atypical morphology and were composed of calcium oxalate. Mount Lofty Ranges koalas unaffected by renal oxalate crystal deposition had renal insufficiency (43%), although only 14% had USG < 1.030 (n = 7). Unaffected Mount Lofty Ranges and Kangaroo Island koalas were hyperoxaluric compared with Queensland koalas (P < .01). Koalas with oxalate nephrosis from the Mount Lofty Ranges had renal insufficiency, hyperoxaluria, and pathognomonic urinary crystals. The findings of this study will aid veterinary diagnosis of this disease. © 2014 American Society for Veterinary Clinical Pathology and European Society for Veterinary Clinical Pathology.

Analytical Study of Oxalates Coprecipitation

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Liana MARTA

2003-03-01

Full Text Available The paper deals with the establishing of the oxalates coprecipitation conditions in view of the synthesis of superconducting systems. A systematic analytical study of the oxalates precipitation conditions has been performed, for obtaining superconducting materials, in the Bi Sr-Ca-Cu-O system. For this purpose, the formulae of the precipitates solubility as a function of pH and oxalate excess were established. The possible formation of hydroxo-complexes and soluble oxalato-complexes was taken into account. A BASIC program was used for tracing the precipitation curves. The curves of the solubility versus pH for different oxalate excess have plotted for the four oxalates, using a logaritmic scale. The optimal conditions for the quantitative oxalate coprecipitation have been deduced from the diagrams. The theoretical curves were confirmed by experimental results. From the precursors obtained by this method, the BSCCO superconducting phases were obtained by an appropriate thermal treatment. The formation of the superconducting phases was identified by X-ray diffraction analysis.

A Study of Biomolecules as Growth Modifiers of Calcium Oxalate Crystals

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Kwak, Junha John

Crystallization processes are ubiquitous in nature, science, and technology. Controlling crystal growth is pivotal in many industries as material properties and functions can be tailored by tuning crystal habits (e.g. size, shape, phase). In biomineralization, organisms exert excellent control over bottom-up synthesis and assembly of inorganic-organic structures (e.g. bones, teeth, exoskeletons). This is made possible by growth modifiers that range from small molecules to macromolecules, such as proteins. Molecular recognition of the mineral phase allows proteins to function as nucleation templates, matrices, and growth inhibitors or promoters. We are interested in taking a biomimetic approach to control crystallization via biomolecular growth modifiers. We investigated calcium oxalate monohydrate (COM), found in plants and kidney stones, as a model system of crystallization. We studied the effects of four common proteins on COM crystallization: bovine serum albumin (BSA), transferrin, lactoferrin, and lysozyme. Through kinetic studies of COM crystallization, we classified BSA and lysozyme as COM growth inhibitor and promoter respectively. Their inhibition and promotion effects were also evident in the macroscopic crystal habit. Through adsorption and microscopy experiments, we showed that BSA exhibits binding specificity for the apical surfaces of macroscopic COM crystals. Lysozyme, on the other, functions via a non-binding mechanism at the surface to accelerate the growth of the apical surfaces. We also synthesized and studied peptides derived from the protein primary sequences to identify putative domains responsible for these inhibition and promotion effects. Collectively, our study of physiologically relevant biomolecules suggests potential roles of COM modifiers in pathological crystallization and helps to develop guidelines for rational design of biomolecular growth modifiers for applications in crystal engineering.

Cerium oxalate precipitation

International Nuclear Information System (INIS)

Chang, T.P.

1987-02-01

Cerium, a nonradioactive, common stand-in for plutonium in development work, has been used to simulate several plutonium precipitation processes at the Savannah River Laboratory. There are similarities between the plutonium trifluoride and the cerium oxalate precipitations in particle size and extent of plating, but not particle morphology. The equilibrium solubility, precipitation kinetics, particle size, extent of plating, and dissolution characteristics of cerium oxalate have been investigated. Interpretations of particle size and plating based on precipitation kinetics (i.e., nucleation and crystal growth) are presented. 16 refs., 7 figs., 6 tabs

Nanoscale observations of the effect of citrate on calcium oxalate precipitation on calcite surfaces.

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Burgos-Cara, Alejandro; Ruiz-Agudo, Encarnacion; Putnis, Christine V.

2016-04-01

Calcium oxalate (CaC2O4ṡxH2O) minerals are naturally occurring minerals found in fossils, plants, kidney stones and is a by-product in some processes such as paper, food and beverage production [1,2]. In particular, calcium oxalate monohydrate phase (COM) also known as whewellite (CaC2O4ṡH2O), is the most frequently reported mineral phase found in urinary and kidney stones together with phosphates. Organic additives are well known to play a key role in the formation of minerals in both biotic and abiotic systems, either facilitating their precipitation or hindering it. In this regard, recent studies have provided direct evidence demonstrating that citrate species could enhance dissolution of COM and inhibit their precipitation. [3,4] The present work aims at evauate the influence of pH, citrate and oxalic acid concentrations in calcium oxalate precipitation on calcite surfaces (Island Spar, Chihuahua, Mexico) through in-situ nanoscale observation using in situ atomic force microscopy (AFM, Multimode, Bruker) in flow-through experiments. Changes in calcium oxalate morphologies and precipitated phases were observed, as well as the inhibitory effect of citrate on calcium oxalate precipitation, which also lead to stabilization an the amorphous calcium oxalate phase. [1] K.D. Demadis, M. Öner, Inhibitory effects of "green"additives on the crystal growth of sparingly soluble salts, in: J.T. Pearlman (Ed.), Green Chemistry Research Trends, Nova Science Publishers Inc., New York, 2009, pp. 265-287. [2] M. Masár, M. Zuborová, D. Kaniansky, B. Stanislawski, Determination of oxalate in beer by zone electrophoresis on a chip with conductivity detection, J. Sep. Sci. 26 (2003) 647-652. [3] Chutipongtanate S, Chaiyarit S, Thongboonkerd V. Citrate, not phosphate, can dissolve calcium oxalate monohydrate crystals and detach these crystals from renal tubular cells. Eur J Pharmacol 2012;689:219-25. [4] Weaver ML, Qiu SR, Hoyer JR, Casey WH, Nancollas GH, De Yoreo JJ

Infusum Daun Alpukat Sebagai Inhibitor Kristalisasi Kalsium Oksalat pada Ginjal (THE AVOCADO LEAVES INFUSUM AS INHIBITOR ON RENAL CALCIUM OXALATE CRYSTALIZATION

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Rini Madyastuti

2016-01-01

Full Text Available Urine crystal is a crystal nucleus which tend to form urine stone. The case of urine stone seems to beincreased every year. Crystallization could induce acute tubular necrosis which impact on renal dysfunction.The signs of this condition are high level of urea, creatinine and decrease glomerulus filtration rate. Theobjective of this research was to evaluate the effects of infusum Persea americana Mill as an inhibitorcrystallization which induced by ethylene glycol on white male rats. 20 male rats were divided into 4groups; K1 as negative group received only distilled water ad libitum, K2 as positive group receiveddistilled water containing ethylene glycol, K3 (dose 5% and K4 (dose 10% as treatment groups receivedwater containing ethylene glycol and avocado leaves infusion. Phytochemsitry screening of infusion avocadoleaves consisted of flavonoid, saponin, tanine and quinone. Result of analysis showed that the level ofureum and creatinine on K2 was higher than K3 and K4 group. The increased level could be inhibited byinfusion avocado leaves. The measurement of glomerular filtration rate in treatment groups wassignificantly different (p<0.05. Descriptive histopathology observation showed that renal lesio in grouptreatment (K3 and K4 were declined. Large crystal calcium oxalate on K2 group was observed by usingpolarized microscope, whereas small crystal calcium oxalate were seen in the infusion of avocado leavesgroups. These result showed the ability of infusion of avocado leaves as an inhibitor on the growth ofcrystallization calcium oxalate

Functional characterization of the oxaloacetase encoding gene and elimination of oxalate formation in the ?-lactam producer Penicillium chrysogenum

NARCIS (Netherlands)

Daran, J.M.; Pronk, J.T.; Driessen, A.J.M.; Nijland, J.G.; Lamboo, F.; Puig-Martinez, M.; Veiga, T.; Gombert, A.K.

2011-01-01

Penicillium chrysogenum is widely used as an industrial antibiotic producer, in particular in the synthesis of ß-lactam antibiotics such as penicillins and cephalosporins. In industrial processes, oxalic acid formation leads to reduced product yields. Moreover, precipitation of calcium oxalate

Physical characteristics of calcium oxalate crystals as determinants in structural defense against chewing insects in Medicago truncatula

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In addition to the numerous chemical defenses that plants employ to fend off insect herbivores, simple structural components can also play important roles in effective protection. Our investigations have shown that plant crystals of calcium oxalate can function in insect defense. The isolation of ca...

New indium selenite-oxalate and indium oxalate with two- and three-dimensional structures

International Nuclear Information System (INIS)

Cao Junjun; Li Guodong; Chen Jiesheng

2009-01-01

Two new indium(III) compounds with extended structures, [In 2 (SeO 3 ) 2 (C 2 O 4 )(H 2 O) 2 ].2H 2 O (I) and [NH 3 (CH 2 ) 2 NH 3 ][In(C 2 O 4 ) 2 ] 2 .5H 2 O (II), have been prepared under mild hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. Compound I crystallizes in the triclinic system, space group P-1, with a=5.2596(11) A, b=6.8649(14) A, c=9.3289(19) A, α=101.78(3) o , β=102.03(3) o , γ=104.52(3) o , while compound II crystallizes in the orthorhombic system, space group Fdd2, with a=15.856(3) A, b=31.183(6) A, c=8.6688(17) A. In compound I, indium-selenite chains are bridged by oxalate units to form two-dimensional (2D) In 2 (SeO 3 ) 2 C 2 O 4 layers, separated by non-coordinating water molecules. In compound II, the indium atoms are connected through the oxalate units to generate a 3D open framework containing cross-linked 12- and 8-membered channels. - Graphical abstract: Two new indium(III) compounds have been hydrothermally synthesized and structurally characterized. In I, the indium-selenite chains are bridged by oxalate units to form 2D In 2 (SeO 3 ) 2 C 2 O 4 layers. In II, the indium atoms are connected through the oxalate units to generate a 3D open framework containing cross-linked 12- and 8-membered ring channels

Metabolic Conversion of l-Ascorbic Acid to Oxalic Acid in Oxalate-accumulating Plants 1

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Yang, Joan C.; Loewus, Frank A.

1975-01-01

l-Ascorbic acid-1-14C and its oxidation product, dehydro-l-ascorbic acid, produced labeled oxalic acid in oxalate-accumulating plants such as spinach seedlings (Spinacia oleracea) and the detached leaves of woodsorrel (Oxalis stricta and O. oregana), shamrock (Oxalis adenopylla), and begonia (Begonia evansiana). In O. oregana, conversion occurred equally well in the presence or absence of light. This relationship between l-ascorbic acid metabolism and oxalic acid formation must be given careful consideration in attempts to explain oxalic accumulation in plants. PMID:16659288

Peeping into human renal calcium oxalate stone matrix: characterization of novel proteins involved in the intricate mechanism of urolithiasis.

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Kanu Priya Aggarwal

Full Text Available BACKGROUND: The increasing number of patients suffering from urolithiasis represents one of the major challenges which nephrologists face worldwide today. For enhancing therapeutic outcomes of this disease, the pathogenic basis for the formation of renal stones is the need of hour. Proteins are found as major component in human renal stone matrix and are considered to have a potential role in crystal-membrane interaction, crystal growth and stone formation but their role in urolithiasis still remains obscure. METHODS: Proteins were isolated from the matrix of human CaOx containing kidney stones. Proteins having MW>3 kDa were subjected to anion exchange chromatography followed by molecular-sieve chromatography. The effect of these purified proteins was tested against CaOx nucleation and growth and on oxalate injured Madin-Darby Canine Kidney (MDCK renal epithelial cells for their activity. Proteins were identified by Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF MS followed by database search with MASCOT server. In silico molecular interaction studies with CaOx crystals were also investigated. RESULTS: Five proteins were identified from the matrix of calcium oxalate kidney stones by MALDI-TOF MS followed by database search with MASCOT server with the competence to control the stone formation process. Out of which two proteins were promoters, two were inhibitors and one protein had a dual activity of both inhibition and promotion towards CaOx nucleation and growth. Further molecular modelling calculations revealed the mode of interaction of these proteins with CaOx at the molecular level. CONCLUSIONS: We identified and characterized Ethanolamine-phosphate cytidylyltransferase, Ras GTPase-activating-like protein, UDP-glucose:glycoprotein glucosyltransferase 2, RIMS-binding protein 3A, Macrophage-capping protein as novel proteins from the matrix of human calcium oxalate stone which play a critical role in kidney stone

4-Methoxybenzamidinium hydrogen oxalate monohydrate

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Simona Irrera

2012-12-01

Full Text Available The title hydrated salt, C8H11N2O+·C2HO4−·H2O, was synthesized by a reaction of 4-methoxybenzamidine (4-amidinoanisole and oxalic acid in water solution. In the cation, the amidinium group forms a dihedral angle of 15.60 (6° with the mean plane of the benzene ring. In the crystal, each amidinium unit is bound to three acetate anions and one water molecule by six distinct N—H...O hydrogen bonds. The ion pairs of the asymmetric unit are joined by two N—H...O hydrogen bonds into ionic dimers in which the carbonyl O atom of the semi-oxalate anion acts as a bifurcated acceptor, thus generating an R12(6 motif. These subunits are then joined through the remaining N—H...O hydrogen bonds to adjacent semi-oxalate anions into linear tetrameric chains running approximately along the b axis. The structure is stabilized by N—H...O and O—H...O intermolecular hydrogen bonds. The water molecule plays an important role in the cohesion and the stability of the crystal structure being involved in three hydrogen bonds connecting two semi-oxalate anions as donor and a benzamidinium cation as acceptor.

On the americium oxalate solubility

International Nuclear Information System (INIS)

Zakolupin, S.A.; Korablin, Eh.V.

1977-01-01

The americium oxalate solubility at different nitric (0.0-1 M) and oxalic (0.0-0.4 M) acid concentrations was investigated in the temperature range from 14 to 60 deg C. The dependence of americium oxalate solubility on the oxalic acid concentration was determined. Increasing oxalic acid concentration was found to reduce the americium oxalate solubility. The dependence of americium oxalate solubility on the oxalic acid concentration was noted to be a minimum at low acidity (0.1-0.3 M nitric acid). This is most likely due to Am(C 2 O 4 ) + , Am(C 2 O 4 ) 2 - and Am(C 2 O 4 ) 3 3- complex ion formation which have different unstability constants. On the basis of the data obtained, a preliminary estimate was carried out for the product of americium oxalate solubility in nitric acid medium (10 -29 -10 -31 ) and of the one in water (6.4x10 -20 )

Functional characterization of the oxaloacetase encoding gene and elimination of oxalate formation in the beta-lactam producer Penicillium chrysogenum

NARCIS (Netherlands)

Gombert, A. K.; Veiga, T.; Puig-Martinez, M.; Lamboo, F.; Nijland, J. G.; Driessen, A. J. M.; Pronk, J. T.; Daran, J. M.

Penicillium chrysogenum is widely used as an industrial antibiotic producer, in particular in the synthesis of g-lactam antibiotics such as penicillins and cephalosporins. In industrial processes, oxalic acid formation leads to reduced product yields. Moreover, precipitation of calcium oxalate

Medicago truncatula-derived calcium oxalate crystals have a negative impact on chewing insect performance via their physical properties

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Plant structural traits often act as defenses against herbivorous insects, causing them to avoid feeding on a given plant or tissue. Mineral crystals of calcium oxalate in Medicago truncatula Gaertn. (Fabaceae) leaves have previously been shown to be effective deterrents of lepidopteran insect feedi...

Effect of Lagenaria siceraria fruit powder on sodium oxalate induced urolithiasis in Wistar rats

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Rahul V Takawale

2012-01-01

Full Text Available Background: In spite of advances in the present practice of medicine, the formation and growth of calculi continues to trouble mankind, as there is no satisfactory drug to treat kidney stones. In India, many indigenous drugs are in use for the treatment of urinary calculus disease. Objective: The present study was intended to determine anti-urolithiatic effect of Lagenaria siceraria fruit powder (LSFP against sodium oxalate (NaOx induced urolithiasis in rats. Materials and Methods: Animals were grouped as Vehicle Group (received vehicle gum acacia 2% w/v 1 mL/kg/p.o., NaOx Group(Sodium oxalate 70 mg/kg,i.p., LSFP Group (500 mg/kg, p.o. LSFP suspended in gum acacia 2% + Sodium oxalate 70 mg/kg, Cystone Group (500 mg/kg, p.o. Cystone suspended in gum acacia 2% + Sodium oxalate 70 mg/kg. Result: The increased severity of microscopic calcium oxalate (CaOx crystals deposition along with increased concentration in the kidney was seen after 7 days of NaOx (70 mg/kg, i.p. pre-treatment. LSFP (500 mg/kg, p.o. and standard marketed formulation Cystone (500 mg/kg, p.o. caused a significant reversal of NaOx-induced changes in ion excretion and urinary CaOx concentration in 7 days treatment. Conclusion: From the results, it was concluded that LSFP showed beneficial effect against urolithiasis by decreasing CaOx excretion and preventing crystal deposition in the kidney tubules.

Investigation of composition and properties of some neptunium (5) oxalate compounds

International Nuclear Information System (INIS)

Zubarev, V.G.; Krot, N.N.

1981-01-01

A simple way of neptunium (5) oxalate synthesis is described and its composition is determined: (NpO 2 ) 2 C 2 O 4 xH 2 O. The compound is precipitated from solution during pouring together stoichiometric quantities of neptunium (5) nitrate and ammonium, sodium or potassium oxalate at pH=4-5. An explanation to unusual effect of solubility change with time of neptunium (5) monooxalate complexes and alkali metal or ammonium ion is found taking into account the slow formation of precipitate and low solubility of the compound obtained (0.62 g/l as to metal). Thermal decomposition of the compound is studied. At 180 deg C a water molecule is split off and at 260 deg C decomposition of neptunium oxalate starts. IR spectra and interplane distances (dsub(hkl)) of the compound crystal lattice are determined. New data on the synthesis and properties of complex neptunium (5) oxalates and monovalent cation in second sphere with the ratio ligand: metal=2:1 and 3:1 are presented. On the basis of results of IR spectroscopy and X-ray phase analyses a supposition is made on the existence of such complex compounds [ru

Characterization of metabolic network of oxalic acid biosynthesis through RNA seq data analysis of developing spikes of finger millet (Eleusine coracana): Deciphering the role of key genes involved in oxalate formation in relation to grain calcium accumulation.

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Akbar, Naved; Gupta, Supriya; Tiwari, Apoorv; Singh, K P; Kumar, Anil

2018-04-05

In the present study, we identified seven major genes of oxalic acid biosynthesis pathway (SGAT, GGAT, ICL, GLO, MHAR, APO and OXO) from developing spike transcriptome of finger millet using rice as a reference. Sequence alignment of identified genes showed high similarity with their respective homolog in rice except for OXO and GLO. Transcript abundance (FPKM) reflects the higher accumulation of identified genes in GP-1 (low calcium genotype) as compared to GP-45 (high calcium genotype) which was further confirmed by qRT-PCR analysis, indicating differential oxalate formation in both genotypes. Determination of oxalic acid and tartaric acid content in developing spikes explain that higher oxalic acid content in GP-1 however, tartaric acid content was more in GP-45. Higher calcium content in GP-45 and lower oxalate accumulation may be due to the diversion of more ascorbic acid into tartaric acid and may correspond to less formation of calcium oxalate. Our results suggest that more than one pathway for oxalic acid biosynthesis might be present in finger millet with probable predominance of ascorbate-tartarate pathway rather than glyoxalate-oxalate conversion. Thus, finger millet can be use as an excellent model system for understanding more specific role of nutrients-antinutrients interactions, as evident from the present study. Copyright © 2018 Elsevier B.V. All rights reserved.

Defining and systematic analyses of aggregation indices to evaluate degree of calcium oxalate crystal aggregation

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Chaiyarit, Sakdithep; Thongboonkerd, Visith

2017-12-01

Crystal aggregation is one of the most crucial steps in kidney stone pathogenesis. However, previous studies of crystal aggregation were rarely done and quantitative analysis of aggregation degree was handicapped by a lack of the standard measurement. We thus performed an in vitro assay to generate aggregation of calcium oxalate monohydrate (COM) crystals with various concentrations (25-800 µg/ml) in saturated aggregation buffer. The crystal aggregates were analyzed by microscopic examination, UV-visible spectrophotometry, and GraphPad Prism6 software to define a total of 12 aggregation indices (including number of aggregates, aggregated mass index, optical density, aggregation coefficient, span, number of aggregates at plateau time-point, aggregated area index, aggregated diameter index, aggregated symmetry index, time constant, half-life, and rate constant). The data showed linear correlation between crystal concentration and almost all of these indices, except only for rate constant. Among these, number of aggregates provided the greatest regression coefficient (r=0.997; pr=0.993; pr=‑0.993; pr=0.991; p<0.001 for both). These five indices are thus recommended as the most appropriate indices for quantitative analysis of COM crystal aggregation in vitro.

Oxalic acid has an additional, detoxifying function in Sclerotinia sclerotiorum pathogenesis.

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Annerose Heller

Full Text Available The mechanism of the diseases caused by the necrotroph plant pathogen Sclerotinia sclerotiorum is not well understood. To investigate the role of oxalic acid during infection high resolution, light-, scanning-, transmission electron microscopy and various histochemical staining methods were used. Our inoculation method allowed us to follow degradation of host plant tissue around single hyphae and to observe the reaction of host cells in direct contact with single invading hyphae. After penetration the outer epidermal cell wall matrix appeared degraded around subcuticular hyphae (12-24 hpi. Calcium oxalate crystals were detected in advanced (36-48 hpi and late (72 hpi infection stages, but not in early stages. In early infection stages, surprisingly, no toxic effect of oxalic acid eventually secreted by S. sclerotiorum was observed. As oxalic acid is a common metabolite in plants, we propose that attacked host cells are able to metabolize oxalic acid in the early infection stage and translocate it to their vacuoles where it is stored as calcium oxalate. The effects, observed on healthy tissue upon external application of oxalic acid to non-infected, living tissue and cell wall degradation of dead host cells starting at the inner side of the walls support this idea. The results indicate that oxalic acid concentrations in the early stage of infection stay below the toxic level. In plant and fungi oxalic acid/calcium oxalate plays an important role in calcium regulation. Oxalic acid likely could quench calcium ions released during cell wall breakdown to protect growing hyphae from toxic calcium concentrations in the infection area. As calcium antimonate-precipitates were found in vesicles of young hyphae, we propose that calcium is translocated to the older parts of hyphae and detoxified by building non-toxic, stable oxalate crystals. We propose an infection model where oxalic acid plays a detoxifying role in late infection stages.

Correlation between oxalic acid production and copper tolerance in Wolfiporia cocos

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C. A. Clausen; Frederick Green; B. M. Woodward; J. W. Evans; R. C. DeGroot

2000-01-01

The increased interest in copper-based wood preservatives has hastened the need for understanding why some fungi are able to attack copper-treated wood. Due in part to accumulation of oxalic acid by brown-rot fungi and visualization of copper oxalate crystals in wood decayed by known copper-tolerant decay fungi, oxalic acid has been implicated in copper tolerance by...

High variability of the heterogeneous ice nucleation potential of oxalic acid dihydrate and sodium oxalate

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R. Wagner

2010-08-01

Full Text Available The heterogeneous ice nucleation potential of airborne oxalic acid dihydrate and sodium oxalate particles in the deposition and condensation mode has been investigated by controlled expansion cooling cycles in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at temperatures between 244 and 228 K. Previous laboratory studies have highlighted the particular role of oxalic acid dihydrate as the only species amongst a variety of other investigated dicarboxylic acids to be capable of acting as a heterogeneous ice nucleus in both the deposition and immersion mode. We could confirm a high deposition mode ice activity for 0.03 to 0.8 μm sized oxalic acid dihydrate particles that were either formed by nucleation from a gaseous oxalic acid/air mixture or by rapid crystallisation of highly supersaturated aqueous oxalic acid solution droplets. The critical saturation ratio with respect to ice required for deposition nucleation was found to be less than 1.1 and the size-dependent ice-active fraction of the aerosol population was in the range from 0.1 to 22%. In contrast, oxalic acid dihydrate particles that had crystallised from less supersaturated solution droplets and had been allowed to slowly grow in a supersaturated environment from still unfrozen oxalic acid solution droplets over a time period of several hours were found to be much poorer heterogeneous ice nuclei. We speculate that under these conditions a crystal surface structure with less-active sites for the initiation of ice nucleation was generated. Such particles partially proved to be almost ice-inactive in both the deposition and condensation mode. At times, the heterogeneous ice nucleation ability of oxalic acid dihydrate significantly changed when the particles had been processed in preceding cloud droplet activation steps. Such behaviour was also observed for the second investigated species, namely sodium oxalate. Our experiments address the atmospheric scenario

High variability of the heterogeneous ice nucleation potential of oxalic acid dihydrate and sodium oxalate

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Wagner, R.; Möhler, O.; Saathoff, H.; Schnaiter, M.; Leisner, T.

2010-08-01

The heterogeneous ice nucleation potential of airborne oxalic acid dihydrate and sodium oxalate particles in the deposition and condensation mode has been investigated by controlled expansion cooling cycles in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at temperatures between 244 and 228 K. Previous laboratory studies have highlighted the particular role of oxalic acid dihydrate as the only species amongst a variety of other investigated dicarboxylic acids to be capable of acting as a heterogeneous ice nucleus in both the deposition and immersion mode. We could confirm a high deposition mode ice activity for 0.03 to 0.8 μm sized oxalic acid dihydrate particles that were either formed by nucleation from a gaseous oxalic acid/air mixture or by rapid crystallisation of highly supersaturated aqueous oxalic acid solution droplets. The critical saturation ratio with respect to ice required for deposition nucleation was found to be less than 1.1 and the size-dependent ice-active fraction of the aerosol population was in the range from 0.1 to 22%. In contrast, oxalic acid dihydrate particles that had crystallised from less supersaturated solution droplets and had been allowed to slowly grow in a supersaturated environment from still unfrozen oxalic acid solution droplets over a time period of several hours were found to be much poorer heterogeneous ice nuclei. We speculate that under these conditions a crystal surface structure with less-active sites for the initiation of ice nucleation was generated. Such particles partially proved to be almost ice-inactive in both the deposition and condensation mode. At times, the heterogeneous ice nucleation ability of oxalic acid dihydrate significantly changed when the particles had been processed in preceding cloud droplet activation steps. Such behaviour was also observed for the second investigated species, namely sodium oxalate. Our experiments address the atmospheric scenario that coating layers

Short communication: Urinary oxalate and calcium excretion by dogs and cats diagnosed with calcium oxalate urolithiasis

NARCIS (Netherlands)

Dijcker, J.C.; Kummeling, A.; Hagen-Plantinga, E.A.; Hendriks, W.H.

2012-01-01

Introduction Urine concentrations of oxalate and calcium play an important role in calcium oxalate (CaOx) urolith formation in dogs and cats, with high excretions of both substances increasing the chance of CaOx urolithiasis. In 17 CaOx-forming dogs, urine calcium:creatinine ratio (Ca:Cr) was found

Update on probiotics for the treatment of calcium oxalate stones

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Di ZHANG

2016-09-01

Full Text Available Urolithiasis is one of the common diseases in urinary system, among which calcium oxalate stone is the most common one with a high recurrence rate. An important pathological factor for the formation of calcium oxalate stone is the increased absorption of oxalate from intestine, which leads to a high urine oxalate concentration. Intestinal bacteria known to be able to degrade oxalate includes Oxalobacter formigenes, Enterococcus faecalis, Escherichia coli, Eubacterium lentum, Providencia rettgeri, Lactobacillus and Bifidobacterium species, etc. Among those, Oxalobacter formigenes is the first oxalate-degrading obligate anaerobe found in human, while the rest are just conditioned bacteria with the function to degrade intestinal oxalate. There are three kinds of enzymes in Oxalobacter formigenes involved in the metabolism of oxalate, namely oxalate-formate antiporter (OxlT, formyl-CoA transferase (Frc and oxalyl-CoA decarboxylase (Oxc. Animal experiments have verified that Oxalobacter formigenes could reduce intestinal oxalate absorption by promoting the secretion of oxalate and degradation as well, thus decrease the excretion of urine oxalate. The present review will focus on the research progress of probiotics treatment for the calcium oxalate stones so as to provide reference for further research and development. DOI: 10.11855/j.issn.0577-7402.2016.08.16

Distribution of calcium oxalate crystals in floral organs of Araceae in relation to pollination strategy.

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Coté, Gary G; Gibernau, Marc

2012-07-01

Many flowers are pollinated by potentially hungry insects, yet flowers also contain gametes and embryos which must be protected from predation. Microscopic calcium oxalate crystals in plant tissues have been proposed to protect against herbivory. Aroids, which have an unusual diversity of such crystals, also exhibit diverse pollination strategies. Many species have pollinators that do not feed while visiting the flowers, while other species, especially those pollinated by beetles, offer sterile staminodia as food rewards. We examined flowers of 21 aroid species with various pollination strategies to test the hypothesis that crystals protect vital gametes and embryos while allowing consumption of food bribes. Aroid inflorescences collected from the field or from greenhouse material were sectioned, cleared, and examined by bright field and polarization microscopy. All species examined, regardless of pollination strategy, arrayed crystals around unshed pollen and ovules. Less vital tissues, such as odoriferous appendages, had few crystals. Staminodia offered as food to beetle pollinators, however, differed greatly between species in their crystal contents. Some had minimal crystals; some had crystals in patterns suggesting they limit beetle feeding; still others had abundant crystals in no obvious pattern. The results are consistent with crystals protecting against insect predation of gametes and embryos. However, the role of crystals in food-bribe staminodia is unclear. They may limit and direct feeding by beetles in some species, while in others they might have no protective role.

Mechanism of formation of oxalate concrements in the presence of ureaseproducing pathogens in urine (conception

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Vozianov S.A.

2017-06-01

Full Text Available The aim of the study was to as¬certain the role of U.urealyticum in formation of phosphates and oxalates in kidneys and factors promoting this pro¬cess. The work represents the author’s conception of this process. There were fully examined 79 patients with nephro¬lithiasis with the aim to determine the species difference of pathogenic agents of the accompanying inflammatory process and there was compared the chemical structure of the removed concrements. There was stated the role of the urease-producing bacteria (P.mirabilis and U.urealyticum in the process of phosphate and oxalate lithogenesis and the accompanying factors, which initiate these reactions (urinary pH, endogenic urease, index of oxalic acid concentration. The work presents the comparative analysis of lithogenesis in the presence of accompanying bacteria of different taxonomic position. The authors’ conception of the role of U.urealyticum and P.mirabilis in lithogenesis has been elaborated.

Uranyl Oxalate Solubility

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Leturcq, G.; Costenoble, S.; Grandjean, S. [CEA Marcoule DEN/DRCP/SCPS/LCA - BP17171 - 30207 Bagnols sur Ceze cedex (France)

2008-07-01

The solubility of uranyl oxalate was determined at ambient temperature by precipitation in oxalic-nitric solutions, using an initial uranyl concentration of 0.1 mol/L. Oxalic concentration varied from 0.075 to 0.3 mol/L while nitric concentration ranged between 0.75 and 3 mol/L. Dissolution tests, using complementary oxalic-nitric media, were carried out for 550 hours in order to study the kinetic to reach thermodynamic equilibrium. Similar solubility values were reached by dissolution and precipitation. Using the results, it was possible to draw the solubility surface versus oxalic and nitric concentrations and to determine both the apparent solubility constant of UO{sub 2}C{sub 2}O{sub 4}, 3H{sub 2}O (Ks) and the apparent formation constant of the first uranyl-oxalate complex UO{sub 2}C{sub 2}O{sub 4} (log {beta}1), for ionic strengths varying between 1 and 3 mol/L. Ks and log {beta}1 values were found to vary from 1.9 10{sup -8} to 9.2 10{sup -9} and from 5.95 to 6.06, respectively, when ionic strength varied from 1 to 3 mol/L. A second model may fit our data obtained at an ionic strength of 3 mol/L suggesting as reported by Moskvin et al. (1959) that no complexes are formed for [H{sup +}] at 3 M. The Ks value would then be 1.3 10{sup -8}. (authors)

Turning sunlight into stone: the oxalate-carbonate pathway in a tropical tree ecosystem

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G. Cailleau

2011-07-01

Full Text Available An African oxalogenic tree, the iroko tree (Milicia excelsa, has the property to enhance carbonate precipitation in tropical oxisols, where such accumulations are not expected due to the acidic conditions in these types of soils. This uncommon process is linked to the oxalate-carbonate pathway, which increases soil pH through oxalate oxidation. In order to investigate the oxalate-carbonate pathway in the iroko system, fluxes of matter have been identified, described, and evaluated from field to microscopic scales. In the first centimeters of the soil profile, decaying of the organic matter allows the release of whewellite crystals, mainly due to the action of termites and saprophytic fungi. In addition, a concomitant flux of carbonate formed in wood tissues contributes to the carbonate flux and is identified as a direct consequence of wood feeding by termites. Nevertheless, calcite biomineralization of the tree is not a consequence of in situ oxalate consumption, but rather related to the oxalate oxidation inside the upper part of the soil. The consequence of this oxidation is the presence of carbonate ions in the soil solution pumped through the roots, leading to preferential mineralization of the roots and the trunk base. An ideal scenario for the iroko biomineralization and soil carbonate accumulation starts with oxalatization: as the iroko tree grows, the organic matter flux to the soil constitutes the litter, and an oxalate pool is formed on the forest ground. Then, wood rotting agents (mainly termites, saprophytic fungi, and bacteria release significant amounts of oxalate crystals from decaying plant tissues. In addition, some of these agents are themselves producers of oxalate (e.g. fungi. Both processes contribute to a soil pool of "available" oxalate crystals. Oxalate consumption by oxalotrophic bacteria can then start. Carbonate and calcium ions present in the soil solution represent the end products of the oxalate

Calcium Oxalate Stones Are Frequently Found Attached to Randall's Plaque

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Matlaga, Brian R.; Williams, James C. Jr.; Evan, Andrew P.; Lingeman, James E.

2007-01-01

The exact mechanisms of the crystallization processes that occur during the formation of calcium oxalate calculi are controversial. Over six decades ago, Alexander Randall reported on a series of cadaveric renal units in which he observed calcium salt deposits on the tips of the renal papilla. Randall hypothesized that these deposits, eponymously termed Randall's plaque, would be the ideal site for stone formation, and indeed in a number of specimens he noted small stones attached to the papillae. With the recent advent of digital endoscopic imaging and micro computerized tomography (CT) technology, it is now possible to inspect the renal papilla of living, human stone formers and to study the attached stone with greater scrutiny

Structural, optical, mechanical and density functional theory studies of 1H-pyrazol-2-ium hydrogen oxalate crystal

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Devi, P. Karthiga, E-mail: karthvi19@gmail.com; Venkatachalam, K.

2016-11-01

In the present work, we have grown 1H- pyrazol-2-ium hydrogen oxalate single crystal by slow evaporation solution growth technique. The lattice parameters are determined from single crystal X ray diffraction studies. The functional groups present in the compound are confirmed by Fourier transform infrared spectroscopy. UV-Vis analysis shows that the crystal has a wide transparency window. Vicker's hardness test has been carried out to estimate the stiffness constant, fracture toughness, brittleness index and yield strength of the crystal. Density functional study B3LYP method at 6-31 G (d, p) has been performed to study the optimized structure, HOMO-LUMO energy gap, hyperpolarizability and thermodynamic properties. - Highlights: • The title compound was analyzed using FTIR and UV–Vis spectroscopy. • Mechanical study was carried out using Vicker's hardness test. • Optimized molecular geometry was determined using DFT method. • Hydrogen bonding interaction was studied through NBO analysis.

Response surface methodology based extraction of Tribulus terrestris leads to an upsurge of antilithiatic potential by inhibition of calcium oxalate crystallization processes

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Kaushik, Jyoti; Tandon, Simran; Gupta, Varun; Nayyar, Jasamrit; Singla, Surinder Kumar; Tandon, Chanderdeep

2017-01-01

Tribulus terrestris has significant antilithiatic efficacy established via both in vitro as well as in vivo studies and is used in numerous anti-urolithiatic herbal formulations viz. Cystone, Uriflow, Uritone and Neeri. However, to fully utilize its antilithiatic potential, the influence of different extraction parameters on antilithiatic ability of T. terrestris aqueous extract needs elucidation. Thus, the current study was undertaken using statistically optimized extraction conditions for aqueous extract preparation. Response surface methodology was employed to observe the influence of three variables i.e. temperature (°C), time (h) and solid: liquid ratio (S: L) on the extraction yield (%) and protein content (mg/g) of T. terrestris aqueous extract. RSM results revealed that the high S:L ratio, low temperature and reduced incubation time were optimal conditions for aqueous extraction. Under such extraction conditions the protein content reached the value of 26.6±1.22 mg/g and the obtained extraction yield was 27.32±1.62%. The assessment of antilithiatic activity of 4 selected extracts (AE1-4), revealed enhanced nucleation and aggregation inhibition of calcium oxalate crystals with AE1 and AE2, which in addition significantly altered the size and morphology of calcium oxalate monohydrate (COM) crystals compared to AE3 and AE4. In vitro cell culture based studies on renal epithelial cells (MDCK, NRK-52E and PK 15) proved that the AE1 showed higher cytoprotective potency by increasing cell viability as compared to the oxalate treated group. The free radical scavenging activity of aqueous extract lowered the reactive oxygen specie’s induced damage and potentially reduced the signals of programmed cell death due to oxalate injury. In addition, modulation of the COM crystal morphology was enhanced by AE1 as compared to AE2. The FTIR and GC-MS analysis of AE1, showed the presence of biomolecules which could aid in the attenuation of lithiatic process. In the light

Response surface methodology based extraction of Tribulus terrestris leads to an upsurge of antilithiatic potential by inhibition of calcium oxalate crystallization processes.

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Kaushik, Jyoti; Tandon, Simran; Gupta, Varun; Nayyar, Jasamrit; Singla, Surinder Kumar; Tandon, Chanderdeep

2017-01-01

Tribulus terrestris has significant antilithiatic efficacy established via both in vitro as well as in vivo studies and is used in numerous anti-urolithiatic herbal formulations viz. Cystone, Uriflow, Uritone and Neeri. However, to fully utilize its antilithiatic potential, the influence of different extraction parameters on antilithiatic ability of T. terrestris aqueous extract needs elucidation. Thus, the current study was undertaken using statistically optimized extraction conditions for aqueous extract preparation. Response surface methodology was employed to observe the influence of three variables i.e. temperature (°C), time (h) and solid: liquid ratio (S: L) on the extraction yield (%) and protein content (mg/g) of T. terrestris aqueous extract. RSM results revealed that the high S:L ratio, low temperature and reduced incubation time were optimal conditions for aqueous extraction. Under such extraction conditions the protein content reached the value of 26.6±1.22 mg/g and the obtained extraction yield was 27.32±1.62%. The assessment of antilithiatic activity of 4 selected extracts (AE1-4), revealed enhanced nucleation and aggregation inhibition of calcium oxalate crystals with AE1 and AE2, which in addition significantly altered the size and morphology of calcium oxalate monohydrate (COM) crystals compared to AE3 and AE4. In vitro cell culture based studies on renal epithelial cells (MDCK, NRK-52E and PK 15) proved that the AE1 showed higher cytoprotective potency by increasing cell viability as compared to the oxalate treated group. The free radical scavenging activity of aqueous extract lowered the reactive oxygen specie's induced damage and potentially reduced the signals of programmed cell death due to oxalate injury. In addition, modulation of the COM crystal morphology was enhanced by AE1 as compared to AE2. The FTIR and GC-MS analysis of AE1, showed the presence of biomolecules which could aid in the attenuation of lithiatic process. In the light

Response surface methodology based extraction of Tribulus terrestris leads to an upsurge of antilithiatic potential by inhibition of calcium oxalate crystallization processes.

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Jyoti Kaushik

Full Text Available Tribulus terrestris has significant antilithiatic efficacy established via both in vitro as well as in vivo studies and is used in numerous anti-urolithiatic herbal formulations viz. Cystone, Uriflow, Uritone and Neeri. However, to fully utilize its antilithiatic potential, the influence of different extraction parameters on antilithiatic ability of T. terrestris aqueous extract needs elucidation. Thus, the current study was undertaken using statistically optimized extraction conditions for aqueous extract preparation. Response surface methodology was employed to observe the influence of three variables i.e. temperature (°C, time (h and solid: liquid ratio (S: L on the extraction yield (% and protein content (mg/g of T. terrestris aqueous extract. RSM results revealed that the high S:L ratio, low temperature and reduced incubation time were optimal conditions for aqueous extraction. Under such extraction conditions the protein content reached the value of 26.6±1.22 mg/g and the obtained extraction yield was 27.32±1.62%. The assessment of antilithiatic activity of 4 selected extracts (AE1-4, revealed enhanced nucleation and aggregation inhibition of calcium oxalate crystals with AE1 and AE2, which in addition significantly altered the size and morphology of calcium oxalate monohydrate (COM crystals compared to AE3 and AE4. In vitro cell culture based studies on renal epithelial cells (MDCK, NRK-52E and PK 15 proved that the AE1 showed higher cytoprotective potency by increasing cell viability as compared to the oxalate treated group. The free radical scavenging activity of aqueous extract lowered the reactive oxygen specie's induced damage and potentially reduced the signals of programmed cell death due to oxalate injury. In addition, modulation of the COM crystal morphology was enhanced by AE1 as compared to AE2. The FTIR and GC-MS analysis of AE1, showed the presence of biomolecules which could aid in the attenuation of lithiatic process. In

Exploring the Therapeutic Mechanism of Desmodium styracifolium on Oxalate Crystal-Induced Kidney Injuries Using Comprehensive Approaches Based on Proteomics and Network Pharmacology

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Jiebin Hou

2018-06-01

Full Text Available Purpose: As a Chinese medicinal herb, Desmodium styracifolium (Osb. Merr (DS has been applied clinically to alleviate crystal-induced kidney injuries, but its effective components and their specific mechanisms still need further exploration. This research first combined the methods of network pharmacology and proteomics to explore the therapeutic protein targets of DS on oxalate crystal-induced kidney injuries to provide a reference for relevant clinical use.Methods: Oxalate-induced kidney injury mouse, rat, and HK-2 cell models were established. Proteins differentially expressed between the oxalate and control groups were respectively screened using iTRAQ combined with MALDI-TOF-MS. The common differential proteins of the three models were further analyzed by molecular docking with DS compounds to acquire differential targets. The inverse docking targets of DS were predicted through the platform of PharmMapper. The protein–protein interaction (PPI relationship between the inverse docking targets and the differential proteins was established by STRING. Potential targets were further validated by western blot based on a mouse model with DS treatment. The effects of constituent compounds, including luteolin, apigenin, and genistein, were investigated based on an oxalate-stimulated HK-2 cell model.Results: Thirty-six common differentially expressed proteins were identified by proteomic analysis. According to previous research, the 3D structures of 15 major constituents of DS were acquired. Nineteen differential targets, including cathepsin D (CTSD, were found using molecular docking, and the component-differential target network was established. Inverse-docking targets including p38 MAPK and CDK-2 were found, and the network of component-reverse docking target was established. Through PPI analysis, 17 inverse-docking targets were linked to differential proteins. The combined network of component-inverse docking target-differential proteins was

Dating oxalate minerals in rock surface deposits

International Nuclear Information System (INIS)

Watchman, A.

2001-01-01

Oxalate minerals are found associated with rocks, mineral coatings, micro-organisms, plants and animals. They are important in archaeology because they have been found intimately associated with organic binders in prehistoric paints. Oxalate minerals also accumulate in the coatings on rock shelter walls and fallen ceiling slabs where they form the natural backing supports for painting and opaque laminates covering engravings. Though the relationship between anthropogenic activity in a rock shelter and oxalate formation is often uncertain, the radiocarbon age of the oxalate may provide the only means for determining the antiquity of a rock painting or engraving. This paper examines the history of dating oxalate minerals at archaeological sites and provides insights into achieving reliable age estimates. (author). 37 refs., 1 fig., 2 tabs

Oxalate metal complexes in aerosol particles: implications for the hygroscopicity of oxalate-containing particles

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T. Furukawa

2011-05-01

Full Text Available Atmospheric aerosols have both a direct and an indirect cooling effect that influences the radiative balance at the Earth's surface. It has been estimated that the degree of cooling is large enough to weaken the warming effect of carbon dioxide. Among the cooling factors, secondary organic aerosols (SOA play an important role in the solar radiation balance in the troposphere as SOA can act as cloud condensation nuclei (CCN and extend the lifespan of clouds because of their high hygroscopic and water soluble nature. Oxalic acid is an important component of SOA, and is produced via several formation pathways in the atmosphere. However, it is not certain whether oxalic acid exists as free oxalic acid or as metal oxalate complexes in aerosols, although there is a marked difference in their solubility in water and their hygroscopicity. We employed X-ray absorption fine structure spectroscopy to characterize the calcium (Ca and zinc (Zn in aerosols collected at Tsukuba in Japan. Size-fractionated aerosol samples were collected for this purpose using an impactor aerosol sampler. It was shown that 10–60% and 20–100% of the total Ca and Zn in the finer particles (<2.1 μm were present as Ca and Zn oxalate complexes, respectively. Oxalic acid is hygroscopic and can thus increase the CCN activity of aerosol particles, while complexes with various polyvalent metal ions such as Ca and Zn are not hygroscopic, which cannot contribute to the increase of the CCN activity of aerosols. Based on the concentrations of noncomplexed and metal-complexed oxalate species, we found that most of the oxalic acid is present as metal oxalate complexes in the aerosols, suggesting that oxalic acid does not always increase the hygroscopicity of aerosols in the atmosphere. Similar results are expected for other dicarboxylic acids, such as malonic and succinic acids. Thus, it is advisable that the cooling effect of organic aerosols should be estimated by including the

Kidney stone matrix proteins ameliorate calcium oxalate monohydrate induced apoptotic injury to renal epithelial cells.

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Narula, Shifa; Tandon, Simran; Singh, Shrawan Kumar; Tandon, Chanderdeep

2016-11-01

Kidney stone formation is a highly prevalent disease, affecting 8-10% of the human population worldwide. Proteins are the major constituents of human kidney stone's organic matrix and considered to play critical role in the pathogenesis of disease but their mechanism of modulation still needs to be explicated. Therefore, in this study we investigated the effect of human kidney stone matrix proteins on the calcium oxalate monohydrate (COM) mediated cellular injury. The renal epithelial cells (MDCK) were exposed to 200μg/ml COM crystals to induce injury. The effect of proteins isolated from human kidney stone was studied on COM injured cells. The alterations in cell-crystal interactions were examined by phase contrast, polarizing, fluorescence and scanning electron microscopy. Moreover, its effect on the extent of COM induced cell injury, was quantified by flow cytometric analysis. Our study indicated the antilithiatic potential of human kidney stone proteins on COM injured MDCK cells. Flow cytometric analysis and fluorescence imaging ascertained that matrix proteins decreased the extent of apoptotic injury caused by COM crystals on MDCK cells. Moreover, the electron microscopic studies of MDCK cells revealed that matrix proteins caused significant dissolution of COM crystals, indicating cytoprotection against the impact of calcium oxalate injury. The present study gives insights into the mechanism implied by urinary proteins to restrain the pathogenesis of kidney stone disease. This will provide a better understanding of the formation of kidney stones which can be useful for the proper management of the disease. Copyright © 2016 Elsevier Inc. All rights reserved.

Applications in environmental bioinorganic: Nutritional and ultrastructural evaluation and calculus of thermodynamic and structural properties of metal-oxalate complexes.

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Tolentino, Terezinha Alves; Bertoli, Alexandre Carvalho; dos Santos Pires, Maíra; Carvalho, Ruy; Labory, Claudia Regina Gontijo; Nunes, Janaira Santana; Bastos, Ana Rosa Ribeiro; de Freitas, Matheus Puggina

2015-01-01

Lead (Pb) is known by its toxicity both for animals and plants. In order to evaluate its toxicity, plants of Brachiaria brizantha were cultivated on nutritive solution of Hoagland during 90 days and submitted to different concentrations of Pb. The content of macro and micronutrients was evaluated and there was a reduction on root content of Ca, besides the lowest dosages of Pb had induced an increase of N, S, Mn, Cu, Zn and Fe. The cell ultrastructure of leaves and roots were analyzed by transmission electronic microscopy (TEM). Among the main alterations occurred there were invaginations on cell walls, the presence of crystals on the root cells, accumulation of material on the interior of cells and vacuolar compartmentalization. On the leaves the degradation of chloroplasts was observed, as well as the increase of vacuoles. Structures for the formation of oxalate crystals were proposed through molecular modeling and thermodynamic stability. Calculi suggest the formation of highly stable metal-oxalate complexes. Copyright © 2015 Elsevier B.V. All rights reserved.

The effects of copper proximity on oxalate production in Fibroporia radiculosa

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Katie M. Jenkins; Carol A. Clausen; Frederick Green III

2014-01-01

Copper remains a key component used in wood preservatives available today. However, the observed tolerance of several critical wood rotting organisms continues to be problematic. Tolerance to copper has been linked to the production and accumulation of oxalate, which precipitates copper into insoluble copper-oxalate crystals, thus inactivating copper ions. The purpose...

Hydrothermal synthesis of uranyl squarates and squarate-oxalates: hydrolysis trends and in situ oxalate formation.

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Rowland, Clare E; Cahill, Christopher L

2010-07-19

We report the synthesis of two uranyl squarates and two mixed-ligand uranyl squarate-oxalates from aqueous solutions under hydrothermal conditions. These products exhibit a range of uranyl building units from squarates with monomers in (UO(2))(2)(C(4)O(4))(5).6NH(4).4H(2)O (1; a = 16.731(17) A, b = 7.280(8) A, c = 15.872(16) A, beta = 113.294(16) degrees , monoclinic, P2(1)/c) and chains in (UO(2))(2)(OH)(2)(H(2)O)(2)(C(4)O(4)) (2; a = 12.909(5) A, b = 8.400(3) A, c = 10.322(4) A, beta = 100.056(7) degrees , monoclinic, C2/c) to two squarate-oxalate polymorphs with dimers in (UO(2))(2)(OH)(C(4)O(4))(C(2)O(4)).NH(4).H(2)O (3; a = 9.0601(7) A, b = 15.7299(12) A, c = 10.5108(8) A, beta = 106.394(1) degrees , monoclinic, P2(1)/n; and 4; a = 8.4469(6) A, b = 7.7589(5) A, c = 10.5257(7) A, beta = 105.696(1) degrees , monoclinic, P2(1)/m). The dominance at low pH of monomeric species and the increasing occurrence of oligomeric species with increasing pH suggests that uranyl hydrolysis, mUO(2)(2+) + nH(2)O right harpoon over left harpoon [(UO(2))(m)(OH)(n)](2m-n) + nH(+), has a significant role in the identity of the inorganic building unit. Additional factors that influence product assembly include in situ hydrolysis of squaric acid to oxalic acid, dynamic metal to ligand concentration, and additional binding modes resulting from the introduction of oxalate anions. These points and the effects of uranyl hydrolysis with changing pH are discussed in the context of the compounds presented herein.

Secondary formation of oxalic acid and related organic species from biogenic sources in a larch forest at the northern slope of Mt. Fuji

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Mochizuki, Tomoki; Kawamura, Kimitaka; Miyazaki, Yuzo; Wada, Ryuichi; Takahashi, Yoshiyuki; Saigusa, Nobuko; Tani, Akira

2017-10-01

To better understand the formation of water-soluble organic aerosols in the forest atmosphere, we measured low molecular weight (LMW) dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, unsaturated fatty acids (UFAs), and water-soluble organic carbon (WSOC) in aerosols from a Larix kaempferi forest located at the northern slope of Mt. Fuji, Japan, in summer 2012. Concentrations of dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, and WSOC showed maxima in daytime. Relative abundance of oxalic acid in LMW dicarboxylic acids was on average 52% and its average concentration was 214 ng m-3. We found that diurnal and temporal variations of oxalic acid are different from those of isoprene and α-pinene, whereas biogenic secondary organic aerosols (BSOAs) derived from isoprene and α-pinene showed similar variations with oxalic acid. The mass concentration ratios of oxalic acid/BSOAs were relatively constant, although a large variation in the concentrations of toluene that is an anthropogenic volatile organic compound was observed. These results suggest that formation of oxalic acid is associated with the oxidation of isoprene and α-pinene with O3 and other oxidants in the forest atmosphere. In addition, concentrations of UFAs were observed, for the first time, to decrease dramatically during daytime in the forest. Mass concentration ratios of azelaic acid to UFAs showed a positive correlation with O3, suggesting that UFAs are oxidized to yield azelaic acid, which may be further decomposed to oxalic acid in the forest atmosphere. We found that contributions of oxalic acid to WSOC are significantly high ranging from 3.7 to 9.7% (average 6.0%). This study demonstrates that forest ecosystem is an important source of oxalic acid and other dicarboxylic acids in the atmosphere.

Pathological features of oxalate nephrosis in a population of koalas (Phascolarctos cinereus) in South Australia.

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Speight, K N; Boardman, W; Breed, W G; Taggart, D A; Woolford, L; Haynes, J I

2013-03-01

The wild and captive koala population of the Mt Lofty Ranges in South Australia has a high level of renal dysfunction in which crystals consistent with calcium oxalate have been observed in the kidneys. This study aimed to describe the pathological features of the renal disease in this population, confirm the composition of renal crystals as calcium oxalate, and determine whether any age or sex predispositions exist for this disease. A total of 51 koalas (28 wild rescues, 23 captive) were examined at necropsy, of which 28 (55%) were found to have gross and/or histological evidence of oxalate nephrosis. Histopathological features included intratubular and interstitial inflammation, tubule dilation, glomerular atrophy, tubule loss, and cortical fibrosis. Calcium oxalate crystals were demonstrated using a combination of polarization microscopy, alizarin red S staining, infrared spectroscopy, and energy-dispersive X-ray analysis with scanning electron microscopy. Uric acid and phosphate deposits were also shown to be present but were associated with minimal histopathological changes. No significant differences were found between the numbers of affected captive and wild rescued koalas; also, there were no sex or age predispositions identified, but it was found that oxalate nephrosis may affect koalas <2 years of age. The findings of this study suggest that oxalate nephrosis is a leading disease in this koala population. Possible causes of this disease are currently under investigation.

Microbial growth on oxalate by a route not involving glyoxylate carboligase

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Blackmore, Maureen A.; Quayle, J. R.

1970-01-01

1. The metabolism of oxalate by the pink-pigmented organisms, Pseudomonas AM1, Pseudomonas AM2, Protaminobacter ruber and Pseudomonas extorquens has been compared with that of the non-pigmented Pseudomonas oxalaticus. 2. During growth on oxalate, all the organisms contain oxalyl-CoA decarboxylase, formate dehydrogenase and oxalyl-CoA reductase. This is consistent with oxidation of oxalate to carbon dioxide taking place via oxalyl-CoA, formyl-CoA and formate as intermediates, and also reduction of oxalate to glyoxylate taking place via oxalyl-CoA. 3. The pink-pigmented organisms, when grown on oxalate, contain l-serine–glyoxylate aminotransferase and hydroxypyruvate reductase but do not contain glyoxylate carboligase. The converse of this obtains in oxalate-grown Ps. oxalaticus. This indicates that, in contrast with Ps. oxalaticus, synthesis of C3 compounds from oxalate by the pink-pigmented organisms occurs by a variant of the `serine pathway' used by Pseudomonas AM1 during growth on C1 compounds. 4. Evidence in favour of this scheme is provided by the finding that a mutant of Pseudomonas AM1 that lacks hydroxypyruvate reductase is not able to grow on oxalate. PMID:5472155

Occurrence and characterisation of calcium oxalate crystals in stems and fruits of Hylocereus costaricensis and Selenicereus megalanthus (Cactaceae: Hylocereeae).

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Viñas, María; Jiménez, Víctor M

2016-10-01

Detailed description about occurrence of calcium oxalate (CaOx) crystals in the edible vine cactus species Hylocereus costaricensis and Selenicereus megalanthus is scarce. Therefore, we evaluated and characterized the presence, morphology and composition of CaOx crystals in both species. Crystals were isolated from greenhouse and in vitro vegetative stems, and from ripe fruit peels and pulp by enzymatic digestion and density centrifugation and quantified with a haemocytometer. Morphologies were studied using scanning electron microscopy, elemental composition with energy-dispersive X-ray spectroscopy and salt composition with X-ray powder diffraction. Analyses conducted confirmed that isolated crystals were exclusively composed by CaOx, both mono- and dihydrated. Highest crystal contents were measured in greenhouse stems, followed by the fruit peels. While very few crystals were quantified in in vitro plants, they were not detected in the fruit pulp at all, which is of advantage for its human consumption and could be linked to mechanisms of seed dispersal through animals. Different crystal morphologies were observed, sometimes varying between genotypes and tissues analysed. This is the first work known to the authors with a detailed characterization of CaOx crystals in vine cacti. Copyright © 2016 Elsevier Ltd. All rights reserved.

Total and soluble oxalate content of some Indian spices.

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Ghosh Das, Sumana; Savage, G P

2012-06-01

Spices, such as cinnamon, cloves, cardamom, garlic, ginger, cumin, coriander and turmeric are used all over the world as flavouring and colouring ingredients in Indian foods. Previous studies have shown that spices contain variable amounts of total oxalates but there are few reports of soluble oxalate contents. In this study, the total, soluble and insoluble oxalate contents of ten different spices commonly used in Indian cuisine were measured. Total oxalate content ranged from 194 (nutmeg) to 4,014 (green cardamom) mg/100 g DM, while the soluble oxalate contents ranged from 41 (nutmeg) to 3,977 (green cardamom) mg/100 g DM. Overall, the percentage of soluble oxalate content of the spices ranged from 4.7 to 99.1% of the total oxalate content which suggests that some spices present no risk to people liable to kidney stone formation, while other spices can supply significant amounts of soluble oxalates and therefore should be used in moderation.

Morphological control of strontium oxalate particles by PSMA-mediated precipitation reaction

Energy Technology Data Exchange (ETDEWEB)

Yu Jiaguo [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)]. E-mail: jiaguoyu@yahoo.com; Tang Hua [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Cheng Bei [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

2005-05-15

In this paper, strontium oxalate particles with different morphologies could be easily obtained by a precipitation reaction of sodium oxalate with strontium chloride in the absence and presence of poly-(styrene-alt-maleic acid) (PSMA). The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. The effects of pH, aging time and concentration of PSMA on the phase structures and morphologies of the as-prepared strontium oxalate particles were investigated and discussed. The results showed that strontium oxalate particles with various morphologies, such as, bi-pyramids, rods, peanuts, and spherical particles, etc., could be obtained by varying the experimental conditions. PSMA promoted the formation of strontium oxalate dihydrate (SOD) phase. Suitable pH values (pH 7 and 8) favor the formation of the peanut-shaped SrC{sub 2}O{sub 4} particles. This research may provide new insight into the control of morphologies and phase structures of strontium oxalate particles and the biomimetic synthesis of novel inorganic materials.

Circular patterns of calcium oxalate monohydrate induced by defective Langmuir-Blodgett film on quartz substrates

Energy Technology Data Exchange (ETDEWEB)

He Jieyu [Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Ouyang Jianming [Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China)], E-mail: toyjm@jnu.edu.cn

2009-01-01

The defective Langmuir-Blodgett (LB) film of dipalmitoylphosphatidylcholine (DPPC) on quartz injured by potassium oxalate (K{sub 2}C{sub 2}O{sub 4}) was used as a model system to induce growth of calcium oxalate crystals. Atomic force microscopy (AFM) indicated that circular defective domains with a diameter of 1-200 {mu}m existed in the LB film. Scanning electron microscopy (SEM) showed circular patterns of aggregated calcium oxalate monohydrate (COM) crystallites were induced by these defective domains. It was ascribed to that the interaction between the negatively-charged oxalate ions and the phosphatidyl groups in DPPC headgroups makes the phospholipid molecules rearranged and exist in an out-of-order state in the LB film, especially at the boundaries of liquid-condensed (LC)/liquid-expanded (LE) phases, which provide much more nucleating sites for COM crystals.

Crystallization of calcium oxalate monohydrate at dipalmitoylphosphatidylcholine monolayers in the presence of chondroitin sulfate A

Science.gov (United States)

Ouyang, Jian-Ming; Deng, Sui-Ping; Zhong, Jiu-Ping; Tieke, Bernd; Yu, Shu-Hong

2004-10-01

The growth and aggregation of calcium oxalate monohydrate (COM) crystals beneath dipalmitoylphosphatidylcholine (DPPC) monolayers in the presence of chondroitin sulfate A (C4S) was systematically examined under different surface pressure. The results indicated that the addition of C4S can inhibit the crystal growth and prevent the aggregation of COM crystals. Under a DPPC monolayer, well-defined three-dimensional hexagonal prisms and three-dimensional rhombus prisms with sharply angled tips were obtained. The DPPC monolayer at a surface pressure of 10 mN/m can match the Ca2+ distance of the (1 bar 0 1) face of COM better than at 20 mN/m. The addition of C4S could cooperatively modulate the interaction strength between the monolayer (or itself) with the specific morphology determining faces such as (1 bar 0 1) and (0 2 0), and thus results in remarkable stabilization of the (1 bar 0 1) faces. The dramatic changes in morphological details were due to the strong electrostatic interactions between the Ca2+-rich (1 bar 0 1) crystal faces of COM and the polyanionic polysaccharide C4S together with the negatively charged sites of the zwitterionic DPPC monolayers. The increase of the concentration of C4S can further enhance the stabilization of the (1 bar 0 1) face.

Plasma oxalic acid and calcium levels in oxalate poisoning

Science.gov (United States)

Zarembski, P. M.; Hodgkinson, A.

1967-01-01

Observations are reported on five cases of suicide or attempted suicide by poisoning with oxalic acid or ethylene glycol. Elevated oxalic acid levels were observed in the plasma, stomach contents, and a number of tissues. Raised oxalic acid levels in plasma were associated with reduced total and ultrafilterable calcium levels. It is suggested that the reduction in plasma total calcium level is due mainly to the deposition of calcium oxalate in the soft tissues, but inhibition of the parathyroid glands may be a contributory factor. Microscopic examination of various tissues indicated that oxalic acid is deposited in the tissues in two forms: (1) crystalline calcium oxalate dihydrate in the kidney and (2) a non-crystalline complex of calcium oxalate and lipid in liver and other tissues. PMID:5602563

Characterization of calcium oxalate biominerals in some (non-Cactaceae) succulent plant species.

Science.gov (United States)

Monje, Paula V; Baran, Enrique J

2010-01-01

The water-accumulating leaves of crassulacean acid metabolism plants belonging to five different families were investigated for the presence of biominerals by infrared spectroscopic and microscopic analyses. Spectroscopic results revealed that the mineral present in succulent species of Agavaceae, Aizoaceae, and Asphodelaceae was calcium oxalate monohydrate (whewellite, CaC2O4 x H2O). Crystals were predominantly found as raphides or solitary crystals of various morphologies. However, representative Crassulaceae members and a succulent species of Asteraceae did not show the presence of biominerals. Overall, these results suggest no correlation between calcium oxalate generation and crassulacean acid metabolism in succulent plants.

Hydroxyproline Metabolism and Oxalate Synthesis in Primary Hyperoxaluria.

Science.gov (United States)

Fargue, Sonia; Milliner, Dawn S; Knight, John; Olson, Julie B; Lowther, W Todd; Holmes, Ross P

2018-06-01

Background Endogenous oxalate synthesis contributes to calcium oxalate stone disease and is markedly increased in the inherited primary hyperoxaluria (PH) disorders. The incomplete knowledge regarding oxalate synthesis complicates discovery of new treatments. Hydroxyproline (Hyp) metabolism results in the formation of oxalate and glycolate. However, the relative contribution of Hyp metabolism to endogenous oxalate and glycolate synthesis is not known. Methods To define this contribution, we performed primed, continuous, intravenous infusions of the stable isotope [ 15 N, 13 C 5 ]-Hyp in nine healthy subjects and 19 individuals with PH and quantified the levels of urinary 13 C 2 -oxalate and 13 C 2 -glycolate formed using ion chromatography coupled to mass detection. Results The total urinary oxalate-to-creatinine ratio during the infusion was 73.1, 70.8, 47.0, and 10.6 mg oxalate/g creatinine in subjects with PH1, PH2, and PH3 and controls, respectively. Hyp metabolism accounted for 12.8, 32.9, and 14.8 mg oxalate/g creatinine in subjects with PH1, PH2, and PH3, respectively, compared with 1.6 mg oxalate/g creatinine in controls. The contribution of Hyp to urinary oxalate was 15% in controls and 18%, 47%, and 33% in subjects with PH1, PH2, and PH3, respectively. The contribution of Hyp to urinary glycolate was 57% in controls, 30% in subjects with PH1, and synthesis in individuals with PH2 and PH3. In patients with PH1, who have the highest urinary excretion of oxalate, the major sources of oxalate remain to be identified. Copyright © 2018 by the American Society of Nephrology.

Synthesis and structural characterisation of mixed An(IV)-An(III) actinide oxalates used as precursors for dedicated fuel or target

International Nuclear Information System (INIS)

Tamain, Christelle; Grandjean, Stephane; Arab Chapelet, Benedicte; Abraham, Francis

2010-01-01

Oxalic co-conversion process plays an important role by producing mixed-actinide compounds used as starting materials as they are particularly suitable precursors of actinide oxide solid solutions. In these oxalate compounds, a mixed crystallographic site which accommodates both elements in spite of their different oxidation states has been established. The charge compensation is ensured by monovalent cations present in the acidic solution. This communication reviews the various mixed-actinide oxalates obtained by crystallization from acidic solution. First, crystallographic structures determined by X-ray diffraction from single crystals are described. Then completing data obtained by powder X-ray diffraction are presented on various systems. The different supramolecular arrangements underline the complexity of An(IV)-An(III)/Ln(III) oxalate system and the need to pursue studies on single crystals. (authors)

In-cloud oxalate formation in the global troposphere: a 3-D modeling study

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S. Myriokefalitakis

2011-06-01

Full Text Available Organic acids attract increasing attention as contributors to atmospheric acidity, secondary organic aerosol mass and aerosol hygroscopicity. Oxalic acid is globally the most abundant dicarboxylic acid, formed via chemical oxidation of gas-phase precursors in the aqueous phase of aerosols and droplets. Its lifecycle and atmospheric global distribution remain highly uncertain and are the focus of this study. The first global spatial and temporal distribution of oxalate, simulated using a state-of-the-art aqueous-phase chemical scheme embedded within the global 3-dimensional chemistry/transport model TM4-ECPL, is here presented. The model accounts for comprehensive gas-phase chemistry and its coupling with major aerosol constituents (including secondary organic aerosol. Model results are consistent with ambient observations of oxalate at rural and remote locations (slope = 1.16 ± 0.14, r² = 0.36, N = 114 and suggest that aqueous-phase chemistry contributes significantly to the global atmospheric burden of secondary organic aerosol. In TM4-ECPL most oxalate is formed in-cloud and less than 5 % is produced in aerosol water. About 62 % of the oxalate is removed via wet deposition, 30 % by in-cloud reaction with hydroxyl radical, 4 % by in-cloud reaction with nitrate radical and 4 % by dry deposition. The in-cloud global oxalate net chemical production is calculated to be about 21–37 Tg yr⁻¹ with almost 79 % originating from biogenic hydrocarbons, mainly isoprene. This condensed phase net source of oxalate in conjunction with a global mean turnover time against deposition of about 5 days, maintain oxalate's global tropospheric burden of 0.2–0.3 Tg, i.e. 0.05–0.1 Tg-C that is about 5–9 % of model-calculated water soluble organic carbon burden.

Addition of calcium compounds to reduce soluble oxalate in a high oxalate food system.

Science.gov (United States)

Bong, Wen-Chun; Vanhanen, Leo P; Savage, Geoffrey P

2017-04-15

Spinach (Spinacia oleracea L.) is often used as a base vegetable to make green juices that are promoted as healthy dietary alternatives. Spinach is known to contain significant amounts of oxalates, which are toxic and, if consumed regularly, can lead to the development of kidney stones. This research investigates adding 50-500mg increments of calcium carbonate, calcium chloride, calcium citrate and calcium sulphate to 100g of raw homogenates of spinach to determine whether calcium would combine with the soluble oxalate present in the spinach. Calcium chloride was the most effective additive while calcium carbonate was the least effective. The formation of insoluble oxalate after incubation at 25°C for 30min is a simple practical step that can be incorporated into the juicing process. This would make the juice considerably safer to consume on a regular basis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Putative Aspergillus niger-induced oxalate nephrosis in sheep : clinical communication

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C.J. Botha

2009-05-01

Full Text Available A sheep farmer provided a maize-based brewer's grain (mieliemaroek and bales of Eragrostis curvula hay to ewes and their lambs, kept on zero-grazing in pens. The 'mieliemaroek' was visibly mouldy. After 14 days in the feedlot, clinical signs, including generalised weakness, ataxia of the hind limbs, tremors and recumbency, were noticed. Six ewes died within a period of 7 days. A post mortem examination was performed on 1 ewe. The carcass appeared to be cachectic with mild effusions into the body cavities; mild lung congestion and pallor of the kidneys were observed. Microscopical evaluation revealed nephrosis and birefringent oxalate crystals in the renal tubules when viewed under polarised light. A provisional diagnosis of oxalate nephrosis with subsequent kidney failure was made. Amongst other fungi, Aspergillus niger was isolated from 'mieliemaroek' samples submitted for fungal culture and identification. As A. niger is known to synthesise oxalates, a qualitative screen to detect oxalic acid in the mieliemaroek and purified A. niger isolates was performed using high-performance liquid chromatography (HPLC. Oxalic acid was detected, which supported a diagnosis of soluble oxalate-induced nephropathy.

Cocrystal Screening of Ibuprofen with Oxalic Acid and Citric Acid via Grinding Method

Science.gov (United States)

Othman, M. F.; Anuar, N.; Rahman, S. Ad; Taifuddin, N. A. Ahmad

2018-05-01

Ibuprofen is a Class II Biological Safety Class (BSC) drugs used for relief of arthritis, as an analgesic and possesses the effect of antiplatelet. The major problem involves in ibuprofen is it has a low solubility and high permeability thus causes an unsatisfactory therapeutic effect to humans. Thus, in this work, alteration of ibuprofen’s physicochemical properties is conducted by means of cocrystallization technique. Co-crystallizations of ibuprofen were prepared with selected coformers using dry grinding and liquid assisted grinding (LAG) techniques in different molar ratios while ethanol and propanol were used as a solvent. The new crystalline forms were identified and characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and fourier transform infrared spectroscopy (FTIR). Analysis for Ibuprofen-Citric acid (IBP-CA) system, co-crystal was successfully formed in 1:2, 1:3, 2:1 and 3:1 molar ratios for neat grinding method although the co-crystal produced is unstable. Meanwhile, for Ibuprofen-Oxalic acid (IBP-OA) system, the co-crystal formation was identified only in 1:1, 1:2 and 1:3 molar ratios for the neat grinding method. LAG method shows that co-crystal formation was unsuccessful in both solvents for IBP-CA, while IBP-OA co-crystal was formed in the molar ratio 1:1, 2:1 and 3:1 in ethanol, and 2:1 and 3:1 in propanol.

Isostructural crystal hydrates of rare-earth metal oxalates at high pressure. From strain anisotropy to dehydration

Energy Technology Data Exchange (ETDEWEB)

Zakharov, Boris A.; Matvienko, Alexander A. [Russian Academy of Ssciences, Novosibirsk (Russian Federation). Inst. of Solid State Chemistry and Mechanochemistry; Novosibirsk State Univ. (Russian Federation); Gribov, Pavel A.; Boldyreva, Elena V. [Russian Academy of Ssciences, Novosibirsk (Russian Federation). Inst. of Solid State Chemistry and Mechanochemistry

2017-07-01

The crystal structures of a series of isostructural rare-earth metal oxalates, (REE){sub 2}(C{sub 2}O{sub 4}){sub 3}.10H{sub 2}O (REE=Sm, Y) and a 1:1 YSm(C{sub 2}O{sub 4}){sub 3}.10H{sub 2}O solid solution, have been studied in situ by single-crystal X-ray diffraction and optical microscopy. The structures were followed from ambient pressure to 6 GPa in a DAC with paraffin as the hydrostatic fluid. Bulk compressibilities, anisotropic lattice strain on hydrostatic compression and the corresponding changes in the atomic coordinates were followed. Discontinuities/sharp changes in the slopes of the pressure dependences of volume and selected cell parameters have been observed for yttrium-containing salts at ∝3.5 GPa. This may be related to the re-distribution of water molecules within the crystal structure. Y{sub 2}(C{sub 2}O{sub 4}){sub 3}.10H{sub 2}O undergoes a partial dehydration at 1 GPa, forming monoclinic Y{sub 2}(C{sub 2}O{sub 4}){sub 3}.6H{sub 2}O as single-crystalline inclusions in the original phase.

Novel organic NLO material bis(N-phenylbiguanidium(1+)) oxalate - A combined X-ray diffraction, DSC and vibrational spectroscopic study of its unique polymorphism

Science.gov (United States)

Matulková, Irena; Císařová, Ivana; Vaněk, Přemysl; Němec, Petr; Němec, Ivan

2017-01-01

Three polymorphic modifications of bis(N-phenylbiguanidium(1+)) oxalate are reported, and their characterization is discussed in this paper. The non-centrosymmetric bis(N-phenylbiguanidium(1+)) oxalate (I), which was obtained from an aqueous solution at 313 K, belongs to the monoclinic space group Cc (a = 6.2560(2) Å, b = 18.6920(3) Å, c = 18.2980(5) Å, β = 96.249(1)°, V = 2127.0(1) Å3, Z = 4, R = 0.0314 for 4738 observed reflections). The centrosymmetric bis(N-phenylbiguanidium(1+)) oxalate (II) was obtained from an aqueous solution at 298 K and belongs to the monoclinic space group P21/n (a = 6.1335(3) Å, b = 11.7862(6) Å, c = 14.5962(8) Å, β = 95.728(2)°, V = 1049.90(9) Å3, Z = 4, R = 0.0420 for 2396 observed reflections). The cooling of the centrosymmetric phase (II) leads to the formation of bis(N-phenylbiguanidium(1+)) oxalate (III) (a = 6.1083(2) Å, b = 11.3178(5) Å, c = 14.9947(5) Å, β = 93.151(2)°, V = 1035.05(8) Å3, Z = 4, R = 0.0345 for 2367 observed reflections and a temperature of 110 K), which also belongs to the monoclinic space group P21/n. The crystal structures of the three characterized phases are generally based on layers of isolated N-phenylbiguanidium(1 +) cations separated by oxalate anions and interconnected with them by several types of N-H...O hydrogen bonds. The observed phases generally differ not only in their crystal packing but also in the lengths and characteristics of their hydrogen bonds. The thermal behaviour of the prepared compounds was studied using the DSC method in the temperature range from 90 K up to a temperature near the melting point of each crystal. The bis(N-phenylbiguanidium(1+)) oxalate (II) crystals exhibit weak reversible thermal effects on the DSC curve at 147 K (heating run). Further investigation of this effect, which was assigned to the isostructural phase transformation, was performed using FTIR, Raman spectroscopy and X-ray diffraction analysis in a wide temperature range.

Mixing state of oxalic acid containing particles in the rural area of Pearl River Delta, China: implication for seasonal formation mechanism of Secondary Organic Aerosol (SOA)

OpenAIRE

Cheng, Chunlei; Li, Mei; Chan, Chak K.; Tong, Haijie; Chen, Changhong; Chen, Duohong; Wu, Dui; Li, Lei; Cheng, Peng; Gao, Wei; Huang, Zhengxu; Li, Xue; Fu, Zhong; Bi, Yanru; Zhou, Zhen

2016-01-01

The formation of oxalic acid and its mixing state in atmospheric particulate matter (PM) were studied using a single particle aerosol mass spectrometer (SPAMS) in the summer and winter of 2014 in Heshan, a supersite in the rural area of the Pearl River Delta (PRD) region in China. Oxalic acid-containing particles accounted for 2.5 % and 2.7 % in total detected ambient particles in summer and winter, respectively. Oxalic acid was measured in particles classified as elemental carb...

Synthesis from zinc oxalate, growth mechanism and optical properties of ZnO nano/micro structures

Energy Technology Data Exchange (ETDEWEB)

Raj, C. Justin; Varma, K.B.R. [Materials Research Centre, Indian Institute of Science, Bangalore 560 012 (India); Joshi, R.K. [Special Center for Nano Sciences, Jawaharlal Nehru University, New Delhi 110067 (India)

2011-11-15

We report the synthesis of various morphological micro to nano structured zinc oxide crystals via simple precipitation technique. The growth mechanisms of the zinc oxide nanostructures such as snowflake, rose, platelets, porous pyramid and rectangular shapes were studied in detail under various growth conditions. The precursor powders were prepared using several zinc counter ions such as chloride, nitrate and sulphate along with oxalic acid as a precipitating agent. The precursors were decomposed by heating in air resulting in the formation of different shapes of zinc oxide crystals. Variations in ZnO nanostructural shapes were possibly due to the counter ion effect. Sulphate counter ion led to unusual rose-shape morphology. Strong ultrasonic treatment on ZnO rose shows that it was formed by irregular arrangement of micro to nano size hexagonal zinc oxide platelets. The X-ray diffraction studies confirmed the wurzite structure of all zinc oxide samples synthesized using different zinc counter ions. Functional groups of the zinc oxalate precursor and zinc oxide were identified using micro Raman studies. The blue light emission spectra of the various morphologies were recorded using luminescence spectrometer. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Atmospheric production of oxalic acid/oxalate and nitric acid/nitrate in the Tampa Bay airshed: Parallel pathways

Science.gov (United States)

Martinelango, P. Kalyani; Dasgupta, Purnendu K.; Al-Horr, Rida S.

Oxalic acid is the dominant dicarboxylic acid (DCA), and it constitutes up to 50% of total atmospheric DCAs, especially in non-urban and marine atmospheres. A significant amount of particulate H 2Ox/oxalate (Ox) occurred in the coarse particle fraction of a dichotomous sampler, the ratio of oxalate concentrations in the PM 10 to PM 2.5 fractions ranged from 1 to 2, with mean±sd being 1.4±0.2. These results suggest that oxalate does not solely originate in the gas phase and condense into particles. Gaseous H 2Ox concentrations are much lower than particulate Ox concentrations and are well correlated with HNO 3, HCHO, and O 3, supporting a photochemical origin. Of special relevance to the Bay Region Atmospheric Chemistry Experiment (BRACE) is the extent of nitrogen deposition in the Tampa Bay estuary. Hydroxyl radical is primarily responsible for the conversion of NO 2 to HNO 3, the latter being much more easily deposited. Hydroxyl radical is also responsible for the aqueous phase formation of oxalic acid from alkenes. Hence, we propose that an estimate of rad OH can be obtained from H 2Ox/Ox production rate and we accordingly show that the product of total oxalate concentration and NO 2 concentration approximately predicts the total nitrate concentration during the same period.

Dynamic process model of a plutonium oxalate precipitator. Final report

Energy Technology Data Exchange (ETDEWEB)

Miller, C.L.; Hammelman, J.E.; Borgonovi, G.M.

1977-11-01

In support of LLL material safeguards program, a dynamic process model was developed which simulates the performance of a plutonium (IV) oxalate precipitator. The plutonium oxalate precipitator is a component in the plutonium oxalate process for making plutonium oxide powder from plutonium nitrate. The model is based on state-of-the-art crystallization descriptive equations, the parameters of which are quantified through the use of batch experimental data. The dynamic model predicts performance very similar to general Hanford oxalate process experience. The utilization of such a process model in an actual plant operation could promote both process control and material safeguards control by serving as a baseline predictor which could give early warning of process upsets or material diversion. The model has been incorporated into a FORTRAN computer program and is also compatible with the DYNSYS 2 computer code which is being used at LLL for process modeling efforts.

Dynamic process model of a plutonium oxalate precipitator. Final report

International Nuclear Information System (INIS)

Miller, C.L.; Hammelman, J.E.; Borgonovi, G.M.

1977-11-01

In support of LLL material safeguards program, a dynamic process model was developed which simulates the performance of a plutonium (IV) oxalate precipitator. The plutonium oxalate precipitator is a component in the plutonium oxalate process for making plutonium oxide powder from plutonium nitrate. The model is based on state-of-the-art crystallization descriptive equations, the parameters of which are quantified through the use of batch experimental data. The dynamic model predicts performance very similar to general Hanford oxalate process experience. The utilization of such a process model in an actual plant operation could promote both process control and material safeguards control by serving as a baseline predictor which could give early warning of process upsets or material diversion. The model has been incorporated into a FORTRAN computer program and is also compatible with the DYNSYS 2 computer code which is being used at LLL for process modeling efforts

Structural diversity of the lanthanide oxalates: Condensation of neodymium oxygen polyhedra under hydrothermal conditions

International Nuclear Information System (INIS)

Mer, A.; Rivenet, M.; Abraham, F.; De Almeida, L.; Grandjean, S.

2013-01-01

New neodymium hydroxo-oxalate and oxalate [Nd 6 (H 2 O) 6 (C 2 O 4 ) 7 (OH) 4 ].4H 2 O (1) and [Nd 2 (H 2 O) 4 (C 2 O 4 ) 3 ].2H 2 O (2) were synthesized by hydrothermal reaction at 150 C between neodymium nitrate and oxalic acid solutions at pH = 10-11 obtained by adding various monoamines. The structures were determined from single-crystal X-ray diffraction data. The two compounds crystallize in the monoclinic system with space group P21/c and a = 17.4384 (11), b = 8.1717 (5), c = 12.9929 (7), β = 94.66 (1) degrees, V = 1845.38 (19) (Angstroms) 3 , Z = 2 for 1 and a = 9.8249 (2) Angstroms, b = 8.2487 (2) Angstroms, c = 10.1911 (3) Angstroms, β = 99.09 (1), V = 815.53 (4) (Angstroms) 3 , Z = 2 for 2. Full matrix least-squares refinement yielded R1 = 0.0365 and 0.0267 for 6033 and 3382 independent reflections for 1 and 2 respectively. In 2, the three-dimensional neodymium oxalate arrangement results from dimeric units of edge shared NdO 9 polyhedra connected through oxalate ions acting as bis-bidentate. In 1, the neodymium atoms are connected through μ2-OH and μ3-OH ions to form a hexa-nuclear inorganic core [Nd 6 (OH) 4 (H 2 O) 6 ] with an un-precedently reported geometry leading to a hexa-nuclear polyhedra block. The blocks are connected through an O-O bridge involving two oxygen atoms of two oxalate ions to build a centipede-like ribbon. The ribbons are further connected through oxalate ions to form a three dimensional neodymium oxalate arrangement. In 1, oxalates adopt four distinct bridging modes of coordination, μ2, μ3, μ4 and μ5. (authors)

Proteomic changes in response to crystal formation in Drosophila Malpighian tubules.

Science.gov (United States)

Chung, Vera Y; Konietzny, Rebecca; Charles, Philip; Kessler, Benedikt; Fischer, Roman; Turney, Benjamin W

2016-04-02

Kidney stone disease is a major health burden with a complex and poorly understood pathophysiology. Drosophila Malpighian tubules have been shown to resemble human renal tubules in their physiological function. Herein, we have used Drosophila as a model to study the proteomic response to crystal formation induced by dietary manipulation in Malpighian tubules. Wild-type male flies were reared in parallel groups on standard medium supplemented with lithogenic agents: control, Sodium Oxalate (NaOx) and Ethylene Glycol (EG). Malpighian tubules were dissected after 2 weeks to visualize crystals with polarized light microscopy. The parallel group was dissected for protein extraction. A new method of Gel Assisted Sample Preparation (GASP) was used for protein extraction. Differentially abundant proteins (p<0.05) were identified by label-free quantitative proteomic analysis in flies fed with NaOx and EG diet compared with control. Their molecular functions were further screened for transmembrane ion transporter, calcium or zinc ion binder. Among these, 11 candidate proteins were shortlisted in NaOx diet and 16 proteins in EG diet. We concluded that GASP is a proteomic sample preparation method that can be applied to individual Drosophila Malpighian tubules. Our results may further increase the understanding of the pathophysiology of human kidney stone disease.

Crystal structure of bis(cyclohexylammonium diphenyldioxalatostannate(IV

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Modou Sarr

2015-02-01

Full Text Available Reaction of oxalic acid and diphenyltin dichloride in the presence of cyclohexylamine led to the formation of the title salt, (C6H14N2[Sn(C6H52(C2O42]. The dianion is made up from an Sn(C6H52 moiety cis-coordinated by two chelating oxalate anions, leading to an overall distorted octahedral coordination geometry of the SnIV atom. The negative charges are compensated by two surrounding cyclohexylammonium cations adopting chair conformations each. In the crystal, anions and cations are linked via a network of N—H...O hydrogen bonds into a layered arrangement parallel to (101.

LITERATURE REVIEW FOR OXALATE OXIDATION PROCESSES AND PLUTONIUM OXALATE SOLUBILITY

Energy Technology Data Exchange (ETDEWEB)

Nash, C.

2012-02-03

A literature review of oxalate oxidation processes finds that manganese(II)-catalyzed nitric acid oxidation of oxalate in precipitate filtrate is a viable and well-documented process. The process has been operated on the large scale at Savannah River in the past, including oxidation of 20 tons of oxalic acid in F-Canyon. Research data under a variety of conditions show the process to be robust. This process is recommended for oxalate destruction in H-Canyon in the upcoming program to produce feed for the MOX facility. Prevention of plutonium oxalate precipitation in filtrate can be achieved by concentrated nitric acid/ferric nitrate sequestration of oxalate. Organic complexants do not appear practical to sequester plutonium. Testing is proposed to confirm the literature and calculation findings of this review at projected operating conditions for the upcoming campaign. H Canyon plans to commence conversion of plutonium metal to low-fired plutonium oxide in 2012 for eventual use in the Mixed Oxide Fuel (MOX) Facility. The flowsheet includes sequential operations of metal dissolution, ion exchange, elution, oxalate precipitation, filtration, and calcination. All processes beyond dissolution will occur in HB-Line. The filtration step produces an aqueous filtrate that may have as much as 4 M nitric acid and 0.15 M oxalate. The oxalate needs to be removed from the stream to prevent possible downstream precipitation of residual plutonium when the solution is processed in H Canyon. In addition, sending the oxalate to the waste tank farm is undesirable. This report addresses the processing options for destroying the oxalate in existing H Canyon equipment.

Origin of Urinary Oxalate

Science.gov (United States)

Holmes, Ross P.; Knight, John; Assimos, Dean G.

2007-04-01

Urinary oxalate is mostly derived from the absorption of ingested oxalate and endogenous synthesis. The breakdown of vitamin C may also contribute small amounts to the urinary oxalate pool. The amount of oxalate absorbed is influenced by the oxalate content of the diet, the concentrations of divalent cations in the gut, the presence of oxalate-degrading organisms, transport characteristics of the intestinal epithelium, and other factors associated with the intestinal environment. Knowledge of pathways associated with endogenous oxalate synthesis is limited. Urinary oxalate excretion can be modified using strategies that limit dietary oxalate absorption and the ingestion of oxalogenic substrates such as hydroxyproline.

Acute oxalate nephropathy due to ′Averrhoa bilimbi′ fruit juice ingestion

Directory of Open Access Journals (Sweden)

G Bakul

2013-01-01

Full Text Available Irumban puli (Averrhoa bilimbi is commonly used as a traditional remedy in the state of Kerala. Freshly made concentrated juice has a very high oxalic acid content and consumption carries a high risk of developing acute renal failure (ARF by deposition of calcium oxalate crystals in renal tubules. Acute oxalate nephropathy (AON due to secondary oxalosis after consumption of Irumban puli juice is uncommon. AON due to A. bilimbi has not been reported before. We present a series of ten patients from five hospitals in the State of Kerala who developed ARF after intake of I. puli fruit juice. Seven patients needed hemodialysis whereas the other three improved with conservative management.

Improving nutritional quality and fungal tolerance in soya bean and grass pea by expressing an oxalate decarboxylase.

Science.gov (United States)

Kumar, Vinay; Chattopadhyay, Arnab; Ghosh, Sumit; Irfan, Mohammad; Chakraborty, Niranjan; Chakraborty, Subhra; Datta, Asis

2016-06-01

Soya bean (Glycine max) and grass pea (Lathyrus sativus) seeds are important sources of dietary proteins; however, they also contain antinutritional metabolite oxalic acid (OA). Excess dietary intake of OA leads to nephrolithiasis due to the formation of calcium oxalate crystals in kidneys. Besides, OA is also a known precursor of β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP), a neurotoxin found in grass pea. Here, we report the reduction in OA level in soya bean (up to 73%) and grass pea (up to 75%) seeds by constitutive and/or seed-specific expression of an oxalate-degrading enzyme, oxalate decarboxylase (FvOXDC) of Flammulina velutipes. In addition, β-ODAP level of grass pea seeds was also reduced up to 73%. Reduced OA content was interrelated with the associated increase in seeds micronutrients such as calcium, iron and zinc. Moreover, constitutive expression of FvOXDC led to improved tolerance to the fungal pathogen Sclerotinia sclerotiorum that requires OA during host colonization. Importantly, FvOXDC-expressing soya bean and grass pea plants were similar to the wild type with respect to the morphology and photosynthetic rates, and seed protein pool remained unaltered as revealed by the comparative proteomic analysis. Taken together, these results demonstrated improved seed quality and tolerance to the fungal pathogen in two important legume crops, by the expression of an oxalate-degrading enzyme. © 2016 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

Synthesis, Crystal structure and Characterization of a New Oxalate ...

Indian Academy of Sciences (India)

in a slightly distorted octahedral environment, by two O atoms from two water molecules and four O atoms of two oxalate anions acting as chelating ligands. ... component for building up supramolecular systems and for participating in hydrogen bonding ... heating rate of 10◦C min−1. 2.2 Synthesis of the complex. Aqueous ...

Concomitant carboxylate and oxalate formation from the activation of CO{sub 2} by a thorium(III) complex

Energy Technology Data Exchange (ETDEWEB)

Formanuik, Alasdair; Ortu, Fabrizio; Mills, David P. [School of Chemistry, The University of Manchester (United Kingdom); Inman, Christopher J. [Department of Chemistry and Biochemistry, School of Life Sciences, University of Sussex, Brighton (United Kingdom); Kerridge, Andrew [Department of Chemistry, Lancaster University (United Kingdom); Castro, Ludovic; Maron, Laurent [LPCNO, CNRA et INSA, Universite Paul Sabatier, Toulouse (France)

2016-12-12

Improving our comprehension of diverse CO{sub 2} activation pathways is of vital importance for the widespread future utilization of this abundant greenhouse gas. CO{sub 2} activation by uranium(III) complexes is now relatively well understood, with oxo/carbonate formation predominating as CO{sub 2} is readily reduced to CO, but isolated thorium(III) CO{sub 2} activation is unprecedented. We show that the thorium(III) complex, [Th(Cp''){sub 3}] (1, Cp''={C_5H_3(SiMe_3)_2-1,3}), reacts with CO{sub 2} to give the mixed oxalate-carboxylate thorium(IV) complex [{Th(Cp'')_2[κ"2-O_2C{C_5H_3-3,3'-(SiMe_3)_2}]}{sub 2}(μ-κ{sup 2}:κ{sup 2}-C{sub 2}O{sub 4})] (3). The concomitant formation of oxalate and carboxylate is unique for CO{sub 2} activation, as in previous examples either reduction or insertion is favored to yield a single product. Therefore, thorium(III) CO{sub 2} activation can differ from better understood uranium(III) chemistry. (copyright 2016 The Authors. Published by Wiley-VCH Verlag GmbH and Co. KGaA.)

Tetrakis(acetonitrilecopper(I hydrogen oxalate–oxalic acid–acetonitrile (1/0.5/0.5

Directory of Open Access Journals (Sweden)

A. Timothy Royappa

2013-10-01

Full Text Available In the title compound, [Cu(CH3CN4](C2HO4·0.5C2H2O4·0.5CH3CN, the CuI ion is coordinated by the N atoms of four acetonitrile ligands in a slightly distorted tetrahedral environment. The oxalic acid molecule lies across an inversion center. The acetonitrile solvent molecule is disordered across an inversion center and was refined with half occupancy. In the crystal, the hydrogen oxalate anions and oxalic acid molecules are linked via O—H...O hydrogen bonds, forming chains along [010].

In vitro anti-inflammatory activity of selected oxalate-degrading probiotic bacteria: potential applications in the prevention and treatment of hyperoxaluria.

Science.gov (United States)

Giardina, Silvana; Scilironi, Cristina; Michelotti, Angela; Samuele, Alberta; Borella, Fabio; Daglia, Maria; Marzatico, Fulvio

2014-03-01

Oxalate (Ox) is a very common component of the human diet, capable to collect in the renal tissue and bind calcium to form calcium oxalate (CaOx) crystals. A supersaturation of CaOx crystal may cause nephrocalcinosis and nephrolithiasis. The inflammation derived from the CaOx crystal accumulation, together with innate or secondary renal alterations, could strongly affect the renal function. In this case a consumption of probiotics with either oxalate-degrading activity at intestinal level and systemic anti-inflammatory activity could be an alternative approach to treat the subjects with excess of urinary oxalate excretion. 11 strains of lactic acid bacteria (Lactobacilli and Bifidobacteria), already included in the list of bacteria safe for the human use, were investigated for their capability to degrade oxalate by mean of RP-HPLC-UV method and modulate inflammation in an in vitro model system based on peripheral blood mononuclear cells. Four promising bacterial strains (Lactobacillus plantarum PBS067, Lactobacillus acidophilus LA-14, Bifidobacterium breve PBS077, Bifidobacterium longum PBS078) were identified as innovative biological tools for the prevention and the therapeutic treatment of hyperoxaluria and the inflammatory events associated to the Ox accumulation. The oxalate-degrading activity of some probiotics and their capability to modulate the release of inflammation mediators could be exploited as a new nutraceutical and therapeutic approach for the treatment of oxalate accumulation and the related inflammatory state. © 2014 Institute of Food Technologists®

Hygroscopic properties of oxalic acid and atmospherically relevant oxalates

Science.gov (United States)

Ma, Qingxin; He, Hong; Liu, Chang

2013-04-01

Oxalic acid and oxalates represent an important fraction of atmospheric organic aerosols, however, little knowledge about the hygroscopic behavior of these particles is known. In this study, the hygroscopic behavior of oxalic acid and atmospherically relevant oxalates (H2C2O4, (NH4)2C2O4, CaC2O4, and FeC2O4) were studied by Raman spectrometry and vapor sorption analyzer. Under ambient relative humidity (RH) of 10-90%, oxalic acid and these oxalates hardly deliquesce and exhibit low hygroscopicity, however, transformation between anhydrous and hydrated particles was observed during the humidifying and dehumidifying processes. During the water adsorption process, conversion of anhydrous H2C2O4, (NH4)2C2O4, CaC2O4, and FeC2O4 to their hydrated particles (i.e., H2C2O4·2H2O, (NH4)2C2O4·H2O, CaC2O4·H2O, and FeC2O4·2H2O) occurred at about 20% RH, 55% RH, 10% RH, and 75% RH, respectively. Uptake of water on hydrated Ca-oxalate and Fe-oxalate particles can be described by a multilayer adsorption isotherm. During the dehumidifying process, dehydration of H2C2O4·2H2O and (NH4)2C2O4·H2O occurred at 5% RH while CaC2O4·H2O and FeC2O4·2H2O did not undergo dehydration. These results implied that hydrated particles represent the most stable state of oxalic acid and oxalates in the atmosphere. In addition, the assignments of Raman shift bands in the range of 1610-1650 cm-1 were discussed according to the hygroscopic behavior measurement results.

Reaction of uranyl nitrate with carboxylic di-acids under hydrothermal conditions. Crystal structure of complexes with L(+)-tartaric and oxalic acids

International Nuclear Information System (INIS)

Thuery, P.

2007-01-01

L(+)-tartaric acid reacts with uranyl nitrate in the presence of KOH, under mild hydrothermal conditions, to give the complex [UO 2 (C 4 H 4 O 6 )(H 2 O)] (1), the first uranyl tartrate to be crystallographically characterized. Each tartrate ligand bridges three uranyl ions, one of them in chelating fashion through proximal carboxylate and hydroxyl groups. The resulting assemblage is two-dimensional, with the uranyl pentagonal bipyramidal coordination polyhedra separated from one another. Prolonged heating of an uranyl tartrate solution resulted in oxidative cleavage of the acid and formation of the oxalate complex [(UO 2 ) 2 (C 2 O 4 ) 2 (OH)Na(H 2 O) 2 ] (2). The bis-bidentate oxalate and bridging hydroxide groups ensure the formation of sheets with corner-sharing uranyl pentagonal bipyramidal coordination polyhedra, in which six-membered metallacycles encompass the sodium ions. These sheets are assembled into a three-dimensional framework through further oxo-bonding of the sodium ions. (authors)

Oxalic acid biosynthesis and oxalacetate acetylhydrolase activity in Streptomyces cattleya

International Nuclear Information System (INIS)

Houck, D.R.; Inamine, E.

1987-01-01

In addition to producing the antibiotic thienamycin, Streptomyces cattleya accumulates large amounts of oxalic acid during the course of a fermentation. Washed cell suspensions were utilized to determine the specific incorporation of carbon-14 into oxalate from a number of labeled organic and amino acids. L-[U- 14 C]aspartate proved to be the best precursor, whereas only a small percentage of label from [1,5- 14 C]citrate was found in oxalate. Cell-free extracts catalyzed the formation of [ 14 C]oxalate and [ 14 C]acetate from L-[U- 14 C]aspartate. When L-[4- 14 C]aspartate was the substrate only [ 14 C]acetate was formed. The cell-free extracts were found to contain oxalacetate acetylhydrolase, the enzyme that catalyzes the hydrolysis of oxalacetate to oxalate and acetate. The enzyme is constitutive and is analogous to enzymes in fungi that produce oxalate from oxalacetate. Properties of the crude enzyme were examined

Literature review for oxalate oxidation processes and plutonium oxalate solubility

Energy Technology Data Exchange (ETDEWEB)

Nash, C. A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2015-10-01

A literature review of oxalate oxidation processes finds that manganese(II)-catalyzed nitric acid oxidation of oxalate in precipitate filtrate is a viable and well-documented process. The process has been operated on the large scale at Savannah River in the past, including oxidation of 20 tons of oxalic acid in F-Canyon. Research data under a variety of conditions show the process to be robust. This process is recommended for oxalate destruction in H-Canyon in the upcoming program to produce feed for the MOX facility. Prevention of plutonium oxalate precipitation in filtrate can be achieved by concentrated nitric acid/ferric nitrate sequestration of oxalate. Organic complexants do not appear practical to sequester plutonium. Testing is proposed to confirm the literature and calculation findings of this review at projected operating conditions for the upcoming campaign.

Determination of water-soluble forms of oxalic and formic acids in soils by ion chromatography

Science.gov (United States)

Karicheva, E.; Guseva, N.; Kambalina, M.

2016-03-01

Carboxylic acids (CA) play an important role in the chemical composition origin of soils and migration of elements. The content of these acids and their salts is one of the important characteristics for agrochemical, ecological, ameliorative and hygienic assessment of soils. The aim of the article is to determine water-soluble forms of same carboxylic acids — (oxalic and formic acids) in soils by ion chromatography with gradient elution. For the separation and determination of water-soluble carboxylic acids we used reagent-free gradient elution ion-exchange chromatography ICS-2000 (Dionex, USA), the model solutions of oxalate and formate ions, and leachates from soils of the Kola Peninsula. The optimal gradient program was established for separation and detection of oxalate and formate ions in water solutions by ion chromatography. A stability indicating method was developed for the simultaneous determination of water-soluble organic acids in soils. The method has shown high detection limits such as 0.03 mg/L for oxalate ion and 0.02 mg/L for formate ion. High signal reproducibility was achieved in wide range of intensities which correspond to the following ion concentrations: from 0.04 mg/g to 10 mg/L (formate), from 0.1 mg/g to 25 mg/L (oxalate). The concentration of formate and oxalate ions in soil samples is from 0.04 to 0.9 mg/L and 0.45 to 17 mg/L respectively.

Irritant contact dermatitis caused by needle-like calcium oxalate crystals, raphides, in Agave tequilana among workers in tequila distilleries and agave plantations.

Science.gov (United States)

Salinas, M L; Ogura, T; Soffchi, L

2001-02-01

It was found that needle-like calcium oxalate crystals, raphides, are found abundantly in all tissues of Agave tequilana plants; thus, 1 droplet (0.03 ml) of juice pressed from leaves contains 100-150 crystals, 30-500 microm in length, sharpened at both ends. In tequila distilleries, 5/6 of the workers who handle the agave stems have experienced the characteristic irritation. In contrast, only 1/3 of workers in agave plantations who harvest agave plants, complain of the irritation. It is confirmed that all the irritation suffered in both distilleries and plantations takes place at bodily locations where the plants come into contact with the worker's skin in the course of their work.

Uranyl oxalate hydrates: structures and IR spectra

International Nuclear Information System (INIS)

Giesting, P.A.; Porter, N.J.; Burns, P.C.

2006-01-01

The novel compound (UO 2 ) 2 C 2 O 4 (OH) 2 (H 2 O) 2 (UrOx2A) and the previously studied compound UO 2 C 2 O 4 (H 2 O) 3 (UrOx3) have been synthesized by mild hydrothermal methods. Single crystal diffraction data collected at 125 K using MoK α radiation and a CCD-based area detector were used to solve and refine the crystal structures by full-matrix least-squares techniques to agreement indices (UrOx2A, UrOx3) wR 2 = 0.037, 0.049 for all data, and R1 0.015, 0.024 calculated for 1285, 2194 unique reflections respectively. The compound UrOx2A is triclinic, space group P1, Z = 1, a = 5.5353(4), b 6.0866(4), c = 7.7686(6) Aa, α = 85.6410(10) , β = 89.7740(10) , γ = 82.5090(10) , V = 258.74(3) Aa 3 . The compound UrOx3 is monoclinic, space group P2 1 /c, Z = 4, a = 5.5921(4), b = 16.9931(13), c = 9.3594(7) Aa, β = 99.5330(10) , V = 877.11(11) Aa 3 . The structures consist of chains of uranyl pentagonal bipyramids connected by oxalate groups and, in UrOx2A, hydroxyl groups; UrOx2A is also notable for its high (2:1) ratio of uranyl to oxalate groups, higher than any observed in other published structures of uranyl oxalates. The structure determined for UrOx3, previously studied by Jayadevan and Chackraburtty (1972); Mikhailov et al. (1999) is in agreement with the previous results; however, the increased precision of the present low-temperature structure refinement allows for the assignment of H atom positions based on the difference Fourier map of electron density. The infrared spectra of these two materials collected at room temperature are also presented and compared with previous work on uranyl oxalate systems. (orig.)

Evidence for a cytoplasmic pathway of oxalate biosynthesis in Aspergillus niger

International Nuclear Information System (INIS)

Kubicek, C.P.; Schreferl-Kunar, G.; Woehrer, W.; Roehr, M.

1988-01-01

Oxalate accumulation of up to 8 g/liter was induced in Aspergillus niger by shifting the pH from 6 to 8. This required the presence of P/sub i/ and a nitrogen source and was inhibited by the protein synthesis inhibitor cycloheximide. Exogenously added 14 CO 2 was not incorporated into oxalate, but was incorporated into acetate and malate, thus indicating the biosynthesis of oxalate by hydrolytic cleavage of oxaloacetate. Inhibition of mitochondrial citrate metabolism by fluorocitrate did not significantly decrease the oxalate yield. The putative enzyme that was responsible for this oxaloacetate hydrolase (EC 3.7.1.1), which was induced de novo during the pH shift. Subcellular fractionation of oxalic acid-forming mycelia of A. niger showed that this enzyme is located in the cytoplasm of A. niger. The results are consistent with a cytoplasmic pathway of oxalate formation which does not involve the tricarboxylic acid cycle

Further Studies on Oxalic Acid Biosynthesis in Oxalate-accumulating Plants 1

Science.gov (United States)

Nuss, Richard F.; Loewus, Frank A.

1978-01-01

l-Ascorbic acid functions as a precursor of oxalic acid in several oxalate-accumulating plants. The present study extends this observation to include Rumex crispus L. (curly dock), Amaranthus retroflexus L. (red root pigweed), Chenopodium album L. (lamb's-quarters), Beta vulgaris L. (sugar beet), Halogeton glomeratus M. Bieb. (halogeton), and Rheum rhabarbarum L. (rhubarb). Several species with low oxalate content are also examined. When l-[1-14C]ascorbic acid is supplied to young seedlings of R. crispus or H. glomeratus, a major portion of the 14C is released over a 24-hour period as 14CO2 and only a small portion is recovered as [14C]oxalate, unlike cuttings from 2- or 4-month-old plants which retain a large part of the 14C as [14C]oxalic acid and release very little 14CO2. Support for an intermediate role of oxalate in the release of 14CO2 from l-[1-14C]ascorbic acid is seen in the rapid release of 14CO2 by R. crispus and H. glomeratus seedlings labeled with [14C]oxalic acid. The common origin of oxalic acid carbon in the C1 and C2 fragment from l-ascorbic acid is demonstrated by comparison of 14C content of oxalic acid in several oxalate-accumulators after cuttings or seedlings are supplied equal amounts of l-[1-14C]- or l-[UL-14C]ascorbic acid. Theoretically, l-[1-14C]ascorbic acid will produce labeled oxalic acid containing three times as much 14C as l-[UL-14C]ascorbic acid when equal amounts of label are provided. Experimentally, a ratio of 2.7 ± 0.5 is obtained in duplicate experiments with six different species. PMID:16660342

MRP-1 and BCRP Promote the Externalization of Phosphatidylserine in Oxalate-treated Renal Epithelial Cells: Implications for Calcium Oxalate Urolithiasis.

Science.gov (United States)

Li, YiFu; Yu, ShiLiang; Gan, XiuGuo; Zhang, Ze; Wang, Yan; Wang, YingWei; An, RuiHua

2017-09-01

To investigate the possible involvement of multidrug resistance-associated protein 1 (MRP-1) and breast cancer resistance protein (BCRP) in the oxalate-induced redistribution of phosphatidylserine (PS) in renal epithelial cell membranes. A western blot analysis was used to examine the MRP-1 and BCRP expression levels. Surface-expressed PS was detected by the annexin V-binding assay. The cell-permeable fluorogenic probe 2,7-dichlorofluorescein diacetate was used to measure the intracellular reactive oxygen species (ROS) level. A rat model of hyperoxaluria was obtained using 0.5% ethylene glycol and 1.0% ammonium chloride. In addition, certain animals received verapamil (50 mg/kg body weight), which is a common inhibitor of MRP-1 and BCRP. The degree of nephrolithiasis was assessed histomorphometrically using sections stained by Pizzolato method and by measuring the calcium oxalate crystal content in the renal tissue. Oxalate produced a concentration-dependent increase in the synthesis of MRP-1 and BCRP. Treatment with MK571 and Ko143 (MRP-1- and BCRP-specific inhibitors, respectively) significantly attenuated the oxalate-induced PS externalization. Adding the antioxidant N-acetyl-l-cysteine significantly reduced MRP-1 and BCRP expression. In vivo, markedly decreased nephrocalcinosis was observed compared with that in the rat model of hyperoxaluria without verapamil treatment. Oxalate induces the upregulation of MRP-1 and BCRP, which act as phospholipid floppases causing PS externalization in the renal epithelial cell membrane. The process is mediated by intracellular ROS production. The ROS-mediated increase in the synthesis of MRP-1 and BCRP can play an important role in hyperoxaluria-promoted calcium oxalate urolithiasis by facilitating phosphatidylserine redistribution in renal epithelial cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Physical simulation of precipitation of radioactive element oxalates by using the harmless neodymium oxalate for studying the agglomeration phenomena

International Nuclear Information System (INIS)

Lalleman, Sophie; Bertrand, Murielle; Plasari, Edouard

2012-01-01

Oxalic precipitation is usually applied in nuclear industry to process radioactive wastes or to recover actinides from a multicomponent solution.This paper deals with the development of methods adapted to a nuclear environment in order to study the agglomeration phenomena during actinide oxalic precipitation.These methods are previously set up with harmless elements that simulate the actinide behaviour: the lanthanides. A parametric study is carried out to quantify the influence of operating parameters on the agglomeration kernel and to determine a kinetic law for this mechanism. The experimental study is performed in a continuous-MSMPR precipitator at steady-state. The method is based on the resolution of two population balances using the moment approach, one for elementary crystals and the other for agglomerates. Provided that the kinetic rates of nucleation and growth are known, the agglomeration kernel can be obtained from a mathematical treatment of the experimental particle size distributions. Results point out that experimental crystal sizes are consistent with an independent kernel. It appears that the agglomeration kernel is directly proportional to supersaturation, increases with temperature but is limited by ionic strength and shear rate. (authors)

Identification of a macromolecular crystal growth inhibitor in human urine as osteopontin

DEFF Research Database (Denmark)

Sørensen, Steen; Justesen, S J; Johnsen, A H

1995-01-01

, an unidentified protein rich in uronic acid, and uropontin have all been described as possessing such activity. We have recently isolated an unknown inhibitor of calcium oxalate crystal growth that co-eluted with trypsin inhibitor in several separation steps, which suggested its identity. The aim of the present......Macromolecules occurring in human urine inhibit the growth and/or aggregation of calcium oxalate crystals and may prevent the formation of kidney stones. Attention has focused particularly on proteins, as these seem to be most responsible for the inhibitory activity; three proteins, nephrocalcin...... study was to outline a simple procedure for isolating and identifying this inhibitor. Purification was done as follows: precipitation of the major proteins (albumin and uromucoid) with trichloroacetic acid, followed by anion exchange chromatography, hydroxyapatite chromatography, anion exchange...

Directed synthesis of crystalline plutonium (III) and (IV) oxalates: accessing redox-controlled separations in acidic solutions

International Nuclear Information System (INIS)

Runde, Wolfgang; Brodnax, Lia F.; Goff, George S.; Bean, Amanda C.; Scott, Brian L.

2009-01-01

Both binary and ternary solid complexes of Pu(III) and Pu(IV) oxalates have been previously reported in the literature. However, uncertainties regarding the coordination chemistry and the extent of hydration of some compounds remain mainly because of the absence of any crystallographic characterization. Single crystals of hydrated oxalates of Pu(III), Pu 2 (C 2 O 4 ) 3 (H 2 O) 6 ·3H 2 O (I) and Pu(IV), KPu(C 2 O 4 ) 2 (OH)·2.5H 2 O (II), were synthesized under moderate hydrothermal conditions and characterized by single crystal X-ray diffraction studies. Compounds I and II are the first plutonium(III) or (IV) oxalate compounds to be structurally characterized via single crystal X-ray diffraction studies. Crystallographic data for I: monoclinic, space group P21/c, a = 11.246(3) A, b = 9.610(3) A, c = 10.315(3) A, Z = 4 and II: monoclinic, space group C2/c, a = 23.234(14) A, b = 7.502(4) A, c = 13.029(7) A, Z = 8.

Reuse of sewage sludge as a catalyst in ozonation – Efficiency for the removal of oxalic acid and the control of bromate formation

International Nuclear Information System (INIS)

Wen, Gang; Pan, Zhi-Hui; Ma, Jun; Liu, Zheng-Qian; Zhao, Lei; Li, Jun-Jing

2012-01-01

Highlights: ► Sewage sludge was converted into catalyst (SBC) and characterized. ► SBC can enhance oxalic acid degradation in ozonation. ► Surface reaction mechanism is responsible for enhancement of ozonation by SBC. ► SBC can control the formation of bromate in ozonation. ► Several combined reasons for the control of bromate formation are proposed. - Abstract: Sewage derived sludge is produced with an annual amount increase of 2% all over the world and it is an urgent issue to be addressed by human being. In the present study, sludge was converted into sludge-based catalyst (SBC) with ZnCl 2 as activation agent and characterized by several methods (e.g., scanning electron microscope, X-ray photoelectron spectroscope and Fourier transform infrared spectroscope). Then it was used as a catalyst to enhance the removal of refractory organic matter, oxalic acid, and to control the formation of bromate (BrO 3 − ) in bench semi-continuous ozonation experiments. The effects of various operating parameters on the control of BrO 3 − formation were investigated. Furthermore, the mechanism for the enhancement of organic matter removal and the control of BrO 3 − formation was discussed as well. Results indicate that the combination of SBC with ozone shows a strong synergistic effect, resulting in a notable improvement on oxalic acid removal. A crucial surface reaction mechanism for the enhancement of organic matter removal is proposed on the basis of negative effect of higher pH and no inhibition effect of tert-butanol. The control for BrO 3 − formation was demonstrated and the reason for its control in the process of O 3 /SBC is the combined effect of SBC reductive properties, ozone exposure decrease and hydrogen peroxide concentration increase.

Electrolytic destruction of oxalate ions in plutonium oxalate supernatant

International Nuclear Information System (INIS)

Michael, K.M.; Talnikar, S.G.; Jambunathan, U.; Kapoor, S.C.; Ramanujam, A.; Venkataraman, N.

1996-01-01

A simple and efficient electrolytic method is described for the destruction of the oxalate ions present in plutonium oxalate supernatant. Using platinum electrode and very little KMnO 4 , in situ generation of Mn 3+ ions is achieved which in turn destroys the oxalate. The use of lower current density helps in achieving maximum current efficiency. The end point is easily detectable by the pink colour of permanganate. By reversing the current, this slight excess of permanganate can be destroyed, thus avoiding the use of hydrogen peroxide. By this simple electrolytic method, the corrosive oxalate ion is completely destroyed and the salt content of the waste solution is considerably reduced. (author). 4 refs., 1 fig., 6 tabs

Evidence for a cytoplasmic pathway of oxalate biosynthesis in Aspergillus niger

Energy Technology Data Exchange (ETDEWEB)

Kubicek, C.P.; Schreferl-Kunar, G.; Woehrer, W.; Roehr, M.

1988-03-01

Oxalate accumulation of up to 8 g/liter was induced in Aspergillus niger by shifting the pH from 6 to 8. This required the presence of P/sub i/ and a nitrogen source and was inhibited by the protein synthesis inhibitor cycloheximide. Exogenously added /sup 14/CO/sub 2/ was not incorporated into oxalate, but was incorporated into acetate and malate, thus indicating the biosynthesis of oxalate by hydrolytic cleavage of oxaloacetate. Inhibition of mitochondrial citrate metabolism by fluorocitrate did not significantly decrease the oxalate yield. The putative enzyme that was responsible for this oxaloacetate hydrolase (EC 3.7.1.1), which was induced de novo during the pH shift. Subcellular fractionation of oxalic acid-forming mycelia of A. niger showed that this enzyme is located in the cytoplasm of A. niger. The results are consistent with a cytoplasmic pathway of oxalate formation which does not involve the tricarboxylic acid cycle.

Destruction of oxalate by reaction with hydrogen peroxide. [Hydrazine oxalate

Energy Technology Data Exchange (ETDEWEB)

Mailen, J.C.; Tallent, O.K.; Arwood, P.C.

1981-09-01

The destruction of oxalate by oxidation to carbon dioxide using hydrogen peroxide was studied as an alternative method for the disposal of oxalate in connection with the possible use of an aqueous hydrazine oxalate solution as a scrubbing agent for solvent cleanup in processes for the recovery of uranium, plutonium, and thorium by solvent extraction. The rate of oxidation of oxalate by hydrogen peroxide in acid solution at the reflux temperature was adequate for process application; reaction half-times at 100/sup 0/C were less than one hour when the hydrogen peroxide concentration was greater than 0.5 M. The reaction was first order with respect to both the oxalate and hydrogen peroxide concentrations and had an activation energy of 58.7 kJ/g-mol. The rate increased with the hydrogen ion concentration as (H/sup +/)/sup 0/ /sup 3/ but was not significantly affected by the presence of 100 ppM of uranium or copper in solution. In the near-neutral hydrazine oxalate solutions, the reaction of either component with hydrogen peroxide was too slow for process application.

Photoluminescent lanthanide-organic bilayer networks with 2,3-pyrazinedicarboxylate and oxalate.

Science.gov (United States)

Soares-Santos, Paula C R; Cunha-Silva, Luís; Paz, Filipe A Almeida; Ferreira, Rute A S; Rocha, João; Carlos, Luís D; Nogueira, Helena I S

2010-04-05

The hydrothermal reaction between lanthanide nitrates and 2,3-pyrazinedicarboxylic acid led to a new series of two-dimensional (2D) lanthanide-organic frameworks: [Ln(2)(2,3-pzdc)(2)(ox)(H(2)O)(2)](n) [where 2,3-pzdc(2-) = 2,3-pyrazinedicarboxylate, ox(2-) = oxalate, and Ln(III) = Ce, Nd, Sm, Eu, Gd, Tb, or Er]. The structural details of these materials were determined by single-crystal X-ray diffraction (for Ce(3+) and Nd(3+)) that revealed the formation of a layered structure. Cationic monolayers of {(infinity)(2)[Ln(2,3-pzdc)(H(2)O)](+)} are interconnected via the ox(2-) ligand leading to the formation of neutral (infinity)(2)[Ln(2)(2,3-pzdc)(2)(ox)(H(2)O)(2)] bilayer networks; structural cohesion of the crystalline packing is reinforced by the presence of highly directional O-H...O hydrogen bonds between adjacent bilayers. Under the employed hydrothermal conditions 2,3-pyrazinedicarboxylic acid can be decomposed into ox(2-) and 2-pyrazinecarboxylate (2-pzc(-)), as unequivocally proved by the isolation of the discrete complex [Tb(2)(2-pzc)(4)(ox)(H(2)O)(6)].10H(2)O. Single-crystal X-ray diffraction of this latter complex revealed its co-crystallization with an unprecedented (H(2)O)(16) water cluster. Photoluminescence measurements were performed for the Nd(3+), Sm(3+), Eu(3+), and Tb(3+) compounds which show, under UV excitation at room temperature, the Ln(3+) characteristic intra-4f(N) emission peaks. The energy level of the triplet states of 2,3-pyrazinedicarboxylic acid (18939 cm(-1)) and oxalic acid (24570 cm(-1)) was determined from the 12 K emission spectrum of the Gd(3+) compound. The (5)D(0) and (5)D(4) lifetime values (0.333 +/- 0.006 and 0.577 +/- 0.017 ms) and the absolute emission quantum yields (0.13 +/- 0.01 and 0.05 +/- 0.01) were determined for the Eu(3+) and Tb(3+) compounds, respectively. For the Eu(3+) compound the energy transfer efficiency arising from the ligands' excited states was estimated (0.93 +/- 0.01).

Adaptable coordination of U(IV) in the 2D-(4,4) uranium oxalate network: From 8 to 10 coordinations in the uranium (IV) oxalate hydrates

International Nuclear Information System (INIS)

Duvieubourg-Garela, L.; Vigier, N.; Abraham, F.; Grandjean, S.

2008-01-01

Crystals of uranium (IV) oxalate hydrates, U(C 2 O 4 ) 2 .6H 2 O (1) and U(C 2 O 4 ) 2 .2H 2 O (2), were obtained by hydrothermal methods using two different U(IV) precursors, U 3 O 8 oxide and nitric U(IV) solution in presence of hydrazine to avoid oxidation of U(IV) into uranyl ion. Growth of crystals of solvated monohydrated uranium (IV) oxalate, U(C 2 O 4 ) 2 .H 2 O.(dma) (3), dma=dimethylamine, was achieved by slow diffusion of U(IV) into a gel containing oxalate ions. The three structures are built on a bi-dimensional complex polymer of U(IV) atoms connected through bis-bidentate oxalate ions forming [U(C 2 O 4 )] 4 pseudo-squares. The flexibility of this supramolecular arrangement allows modifications of the coordination number of the U(IV) atom which, starting from 8 in 1 increases to 9 in 3 and, finally increases, to 10 in 2. The coordination polyhedron changes from a distorted cube, formed by eight oxygen atoms of four oxalate ions, in 1, to a mono-capped square anti-prism in 3 and, finally, to a di-capped square anti-prism in 2, resulting from rotation of the oxalate ions and addition of one and two water oxygen atoms in the coordination of U(IV). In 1, the space between the ∞ 2 [U(C 2 O 4 ) 2 ] planar layers is occupied by non-coordinated water molecules; in 2, the space between the staggered ∞ 2 [U(C 2 O 4 ) 2 .2H 2 O] layers is empty, finally in 3, the solvate molecules occupy the interlayer space between corrugated ∞ 2 [U(C 2 O 4 ) 2 .H 2 O] sheets. The thermal decomposition of U(C 2 O 4 ) 2 .6H 2 O under air and argon atmospheres gives U 3 O 8 and UO 2 , respectively. - Graphical abstract: The adaptable environment of U(IV) in U(IV) oxalates: from eight cubic coordination in U(C 2 O 4 ) 2 .6H 2 O (a) completed by water oxygens to nine in [U(C 2 O 4 ) 2 .H 2 O](C 2 NH 5 ) (b) and ten coordination in U(C 2 O 4 ) 2 .2H 2 O (c)

an oxalate-peroxide complex used in the preparation of doped barium titanate

NARCIS (Netherlands)

van der Gijp, S.; Winnubst, Aloysius J.A.; Verweij, H.

1998-01-01

A method is described for the preparation of homogeneously doped barium titanate, which can be applied in non-linear dielectric elements. Ba and Ti salts are dissolved, mixed with hydrogen peroxide and added to a solution of ammonium oxalate, resulting in the formation of an insoluble peroxo-oxalate

Successful treatment of sodium oxalate induced urolithiasis with Helichrysum flowers.

Science.gov (United States)

Onaran, Metin; Orhan, Nilüfer; Farahvash, Amirali; Ekin, Hasya Nazlı; Kocabıyık, Murat; Gönül, İpek Işık; Şen, İlker; Aslan, Mustafa

2016-06-20

Helichrysum (Asteraceae) flowers, known as "altın otu, yayla çiçeği, kudama çiçeği" , are widely used to remove kidney stones and for their diuretic properties in Turkey. To determine the curative effect of infusions prepared from capitulums of Helichrysum graveolens (M. Bieb.) Sweet (HG) and H. stoechas ssp. barellieri (Ten.) Nyman (HS) on sodium oxalate induced kidney stones. Infusions prepared from the capitulums of HG and HS were tested for their curative effect on calcium oxalate deposition induced by sodium oxalate (70mg/kg i.p.). Following the injection of sodium oxalate for 5 days, plant extracts were administered to rats at two different doses. Potassium citrate was used as positive control. Water intake, urine volume, body, liver and kidney weights were measured; biochemical and hematological analyses were conducted on urine and blood samples. Additionally, histopathological examinations were done on kidney samples. H. stoechas extract showed prominent effect at 156mg/kg dose (stone formation score: 0.33), whereas number of kidney stones was maximum in sodium oxalate group (stone formation score: 2.33). The reduction in the uric acid and oxalate levels of urine samples and the elevation in the urine citrate levels are significant and promising in extract groups. Some hematological, biochemical and enzymatic markers are also ameliorated by the extracts. This is the first report on the curative effect of immortal flowers. Our preliminary study indicated that Helichrysum extracts may be used for treatment of urolithiasis and Helichrysum extracts are an alternative therapy to potassium citrate for patients suffering from kidney stones. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Primary Nonfunction of Renal Allograft Secondary to Acute Oxalate Nephropathy

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Ravi Parasuraman

2011-01-01

Full Text Available Primary nonfunction (PNF accounts for 0.6 to 8% of renal allograft failure, and the focus on causes of PNF has changed from rejection to other causes. Calcium oxalate (CaOx deposition is common in early allograft biopsies, and it contributes in moderate intensity to higher incidence of acute tubular necrosis and poor graft survival. A-49-year old male with ESRD secondary to polycystic kidney disease underwent extended criteria donor kidney transplantation. Posttransplant, patient developed delayed graft function (DGF, and the biopsy showed moderately intense CaOx deposition that persisted on subsequent biopsies for 16 weeks, eventually resulting in PNF. The serum oxalate level was 3 times more than normal at 85 μmol/L (normal <27 μmol/L. Allograft nephrectomy showed massive aggregates of CaOx crystal deposition in renal collecting system. In conclusion, acute oxalate nephropathy should be considered in the differential diagnosis of DGF since optimal management could change the outcome of the allograft.

Effects of storage time and temperature on pH, specific gravity, and crystal formation in urine samples from dogs and cats.

Science.gov (United States)

Albasan, Hasan; Lulich, Jody P; Osborne, Carl A; Lekcharoensuk, Chalermpol; Ulrich, Lisa K; Carpenter, Kathleen A

2003-01-15

To determine effects of storage temperature and time on pH and specific gravity of and number and size of crystals in urine samples from dogs and cats. Randomized complete block design. 31 dogs and 8 cats. Aliquots of each urine sample were analyzed within 60 minutes of collection or after storage at room or refrigeration temperatures (20 vs 6 degrees C [68 vs 43 degrees F]) for 6 or 24 hours. Crystals formed in samples from 11 of 39 (28%) animals. Calcium oxalate (CaOx) crystals formed in vitro in samples from 1 cat and 8 dogs. Magnesium ammonium phosphate (MAP) crystals formed in vitro in samples from 2 dogs. Compared with aliquots stored at room temperature, refrigeration increased the number and size of crystals that formed in vitro; however, the increase in number and size of MAP crystals in stored urine samples was not significant. Increased storage time and decreased storage temperature were associated with a significant increase in number of CaOx crystals formed. Greater numbers of crystals formed in urine aliquots stored for 24 hours than in aliquots stored for 6 hours. Storage time and temperature did not have a significant effect on pH or specific gravity. Urine samples should be analyzed within 60 minutes of collection to minimize temperature- and time-dependent effects on in vitro crystal formation. Presence of crystals observed in stored samples should be validated by reevaluation of fresh urine.

Crystal structure and spectroscopic analysis of a new oxalate-bridged MnII compound: catena-poly[guanidinium [[aquachloridomanganese(II]-μ2-oxalato-κ4O1,O2:O1′,O2′] monohydrate

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Hiba Sehimi

2016-05-01

Full Text Available As part of our studies on the synthesis and the characterization of oxalate-bridged compounds M–ox–M (ox = oxalate dianion and M = transition metal ion, we report the crystal structure of a new oxalate-bridged MnII phase, {(CH6N3[Mn(C2O4Cl(H2O]·H2O}n. In the compound, a succession of MnII ions (situated on inversion centers adopting a distorted octahedral coordination and bridged by oxalate ligands forms parallel zigzag chains running along the c axis. These chains are interconnected through O—H...O hydrogen-bonding interactions to form anionic layers parallel to (010. Individual layers are held together via strong hydrogen bonds involving the guanidinium cations (N—H...O and N—H...Cl and the disordered non-coordinating water molecule (O—H...O and O—H...Cl, as well as by guanidinium π–π stacking. The structural data were confirmed by IR and UV–Visible spectroscopic analysis.

Oxalic acid overproduction by copper-tolerant brown-rot basidiomycetes on southern yellow pine treated with copper-based preservatives

Science.gov (United States)

Carol A. Clausen; Frederick Green

2003-01-01

Accumulation of oxalic acid (OA) by brown-rot fungi and precipitation of copper oxalate crystals in wood decayed by copper-tolerant decay fungi has implicated OA in the mechanism of copper tolerance. Understanding the role of OA in copper tolerance is important due to an increasing reliance on copper-based wood preservatives. In this study, four copper-tolerant brown-...

Growth and study of barium oxalate single crystals in agar gel

Indian Academy of Sciences (India)

Unknown

tive Powder Diffraction Data Interpretation and Indexing. Program, Version 2.2) was used to calculate 'd' values. Calculated 'd' values matched with reported values. Table. 2 shows calculated unit cell parameters. Table 2. Calculated unit cell parameters. Parameters. Barium oxalate. System. Monoclinic (P) a. 8⋅2426 Å b.

Function and X-ray crystal structure of Escherichia coli YfdE.

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Elwood A Mullins

Full Text Available Many food plants accumulate oxalate, which humans absorb but do not metabolize, leading to the formation of urinary stones. The commensal bacterium Oxalobacter formigenes consumes oxalate by converting it to oxalyl-CoA, which is decarboxylated by oxalyl-CoA decarboxylase (OXC. OXC and the class III CoA-transferase formyl-CoA:oxalate CoA-transferase (FCOCT are widespread among bacteria, including many that have no apparent ability to degrade or to resist external oxalate. The EvgA acid response regulator activates transcription of the Escherichia coli yfdXWUVE operon encoding YfdW (FCOCT, YfdU (OXC, and YfdE, a class III CoA-transferase that is ~30% identical to YfdW. YfdW and YfdU are necessary and sufficient for oxalate-induced protection against a subsequent acid challenge; neither of the other genes has a known function. We report the purification, in vitro characterization, 2.1-Å crystal structure, and functional assignment of YfdE. YfdE and UctC, an orthologue from the obligate aerobe Acetobacter aceti, perform the reversible conversion of acetyl-CoA and oxalate to oxalyl-CoA and acetate. The annotation of YfdE as acetyl-CoA:oxalate CoA-transferase (ACOCT expands the scope of metabolic pathways linked to oxalate catabolism and the oxalate-induced acid tolerance response. FCOCT and ACOCT active sites contain distinctive, conserved active site loops (the glycine-rich loop and the GNxH loop, respectively that appear to encode substrate specificity.

Surface analysis of transition metal oxalates: Damage aspects

Energy Technology Data Exchange (ETDEWEB)

Chenakin, S.P., E-mail: chenakin@imp.kiev.ua [Université Libre de Bruxelles (ULB), Chimie-Physique des Matériaux, B-1050 Bruxelles (Belgium); Institute of Metal Physics, Nat. Acad. Sci. of Ukraine, Akad. Vernadsky Blvd. 36, 03680 Kiev (Ukraine); Szukiewicz, R. [Université Libre de Bruxelles (ULB), Chimie-Physique des Matériaux, B-1050 Bruxelles (Belgium); Barbosa, R.; Kruse, N. [Université Libre de Bruxelles (ULB), Chimie-Physique des Matériaux, B-1050 Bruxelles (Belgium); Voiland School of Chemical Engineering and Bioengineering, Washington State University, 155 Wegner Hall, Pullman, WA 99164-6515 (United States)

2016-05-15

Highlights: • Gas evolution from the Mn, Co, Ni and Cu oxalate hydrates in vacuum, during exposure to X-rays and after termination of X-ray irradiation is studied. • A comparative study of the damage caused by X-rays in NiC{sub 2}O{sub 4} and CuC{sub 2}O{sub 4} is carried out. • Effect of Ar{sup +} bombardment on the structure and composition of CoC{sub 2}O{sub 4} is studied. - Abstract: The behavior of transition metal oxalates in vacuum, under X-ray irradiation and low-energy Ar{sup +} ion bombardment was studied. A comparative mass-spectrometric analysis was carried out of gas evolution from the surface of Mn, Co, Ni and Cu oxalate hydrates in vacuum, during exposure to X-rays and after termination of X-ray irradiation. The rates of H{sub 2}O and CO{sub 2} liberation from the oxalates were found to be in an inverse correlation with the temperatures of dehydration and decomposition, respectively. X-ray photoelectron spectroscopy (XPS) was employed to study the X-ray induced damage in NiC{sub 2}O{sub 4} and CuC{sub 2}O{sub 4} by measuring the various XP spectral characteristics and surface composition of the oxalates as a function of time of exposure to X-rays. It was shown that Cu oxalate underwent a significantly faster degradation than Ni oxalate and demonstrated a high degree of X-ray induced reduction from the Cu{sup 2+} to the Cu{sup 1+} chemical state. 500 eV Ar{sup +} sputter cleaning of CoC{sub 2}O{sub 4} for 10 min was found to cause a strong transformation of the oxalate structure which manifested itself in an appreciable alteration of the XP core-level and valence band spectra. The analysis of changes in stoichiometry and comparison of XP spectra of bombarded oxalate with respective spectra of a reference carbonate CoCO{sub 3} implied that the bombardment-induced decomposition of CoC{sub 2}O{sub 4} gave rise to the formation of CoO-like and disordered CoCO{sub 3}-like phases.

A novel 3D framework indium phosphite-oxalate based on a pcu-type topology

International Nuclear Information System (INIS)

Zuo, Mengmeng; Zhou, Mingdong; Hu, Dianwen; Gao, Fan; Dong, Sijie; Huang, Liangliang

2016-01-01

A new inorganic–organic hybrid indium phosphite-oxalate, formulated as H[In 5 (HPO 3 ) 6 (H 2 PO 3 ) 2 (C 2 O 4 ) 2 ]·(C 4 N 2 H 11 ) 2 ·H 2 O 1 has been hydrothermally synthesized in the presence of piperazine acting as a structure directing agent (SDA). The single crystal X-ray diffraction reveals that compound 1 shows three-dimensional open-framework with intersecting 12-ring channels along the [010] and [001] directions, which is constructed from strictly alternating double 6-ring units (D6Rs), [C 2 O 4 ] 2− groups and [H 2 PO 3 ] − pseudo-pyramids. It is noted that the classical D6R SBU is firstly reported in main metal phosphite/phosphite-oxalate. By regarding D6R as the 6-connected nodes, the inorganic–organic hybrid framework is based on a pcu-type topology. The as-synthesized product was characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis (TGA), ICP-AES and elemental analyses. - Graphical abstract: A 3D open-framework indium phosphite-oxalate has been synthesized under hydrothermal conditions. A classical SBU, D6R, is present in the structure. By regarding D6R as the 6-connected nodes, the inorganic–organic hybrid framework is based on a pcu-type topology. - Highlights: • A new indium phosphite-oxalate based on a pcu-type topology has been synthesized. • A classical SBU, D6R, is present in the structure. • The classical SBU is firstly reported in main metal phosphite/phosphite-oxalate.

Thorium oxalate solubility and morphology

International Nuclear Information System (INIS)

Monson, P.R. Jr.; Hall, R.

1981-10-01

Thorium was used as a stand-in for studying the solubility and precipitation of neptunium and plutonium oxalates. Thorium oxalate solubility was determined over a range of 0.001 to 10.0 in the concentration parameter [H 2 C 2 O 4 ]/[HNO 3 ] 2 . Morphology of thorium oxide made from the oxalate precipitates was characterized by scanning electron microscopy. The different morphologies found for oxalate-lean and oxalate-rich precipitations were in agreement with predictions based on precipitation theory

Surface activation of MnNb{sub 2}O{sub 6} nanosheets by oxalic acid for enhanced photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Wu, Junshu; Wang, Jinshu, E-mail: wangjsh@bjut.edu.cn; Li, Hongyi; Li, Yongli; Du, Yucheng; Yang, Yilong; Jia, Xinjian

2017-05-01

Graphical abstract: Visible light driven photoreduction of Cr(VI) over MnNb{sub 2}O{sub 6} nanosheets is enhanced via oxalic acid surface complex to generate activation layer. - Highlights: • MnNb{sub 2}O{sub 6} nanosheets are crystallized by a surface capping route of sulfonate groups. • Oxalic acid on MnNb{sub 2}O{sub 6} nanosheets forms an excited surface complex hybrid layer. • Surface activation enhances visible-light induced reduction of Cr(VI) into Cr(III). - Abstract: MnNb{sub 2}O{sub 6} nanosheets (P-MNOs) is selectively crystallized by using surface capping ligand with functional sulfonate group (sodium dodecyl benzene sulphonate), which binds to the (131) surface of MnNb{sub 2}O{sub 6} inducing the morphology-controlled crystallization of MnNb{sub 2}O{sub 6} materials. Surface modification of photoactive P-MNOs with electron-rich oxalic acid ligands establishes an excited surface complex layer on phase-pure P-MNO as evidenced by spectroscopic analyses (FT-IR, UV–vis, Raman, PL, etc.), and thus more efficiently photocatalyzes the reduction of Cr(VI) into Cr(III) than solely P-MNOs or oxalic acid under visible light (λ > 420 nm) via a ligand-to-metal interfacial electron transfer pathway. However, the interaction between oxalic acid and MnNb{sub 2}O{sub 6} is highly dependent upon the morphology of solid MnNb{sub 2}O{sub 6} substrate due to the higher surface-area-to-volume ratio and higher surface activity of (131) planes in the sheet-like morphology. This study could assist the construction of stable niobate material systems to allow a versatile solid surface activation for establishing more energy efficient and robust catalysis process under visible light.

Investigation on clean-up of Zr and HDBP in PUREX process with UDMH oxalate

International Nuclear Information System (INIS)

Zhang Youzhi; Wang Xuanjun; Li Zhengli; Liu Xiangxuan

2007-01-01

It is generally accepted that the interracial crud formation is related to the complex formation of Zr with degradation products of TBP, such as DBP and MBP, in PUREX process, especially in the first cycle. The crud seriously deteriorates the operation of extraction column and therefore must be properly cleared up. Various clear up methods were studied and those with salt-free washing agents were recently focused. In this paper a new scrubbing agent 1,1- dimethylhydrazine (UDMH) oxalate was proposed, the optimized experimental conditions were described, and the possible mechanism was discussed. The influence of different factors, including reaction temperature, UDMH oxalate concentration, organic-to-aqueous phase ratio, and free UDMH concentration, on the decontamination factors were examined with simulated Zr- and/or DBP-loaded solvents. The optical experimental parameters are found as follows: temperature 40-60 degree C, phase ratio V (o) /V (a) =1, concentration of UDMH oxalate solution 0.4-0.6 mol/L. Especialy some UDMH was added into the UDMH oxalate queues solution to make the concentration of free UDMH 0.2-0.3 mol/L. Under these conditions, the decontaminator factor of Zr from the corresponding simulated solvent with UDMH oxalate is up to 143, slightly higher than that with sodium carbonate. The decontamination factor of HDBP from the corresponding simulated solvent with UDMH oxalate is up to 100, similar to sodium carbonate. (authors)

Crystals seen on CSF microscopy in a case of suspected subarachnoid haemorrhage

Science.gov (United States)

Weiand, Daniel; Hanning, Ian; Mouhamadou, Moussa; Wearmouth, Debbie

2015-01-01

Although crystals are rarely identified on cerebrospinal fluid (CSF) microscopy, their presence can be of significant diagnostic value. We report a case of oxalate crystals seen on CSF microscopy of a 43-year-old woman. The patient presented with headaches, nausea and vomiting. CT of the head showed a small focus of hyper-density, suspicious of haemorrhage, in the right side of the pontine cistern. CSF cell count was within the normal range. Although no organisms were seen on microscopy, copious oxalate crystals were seen. The same crystals were seen on microscopy of CSF collected in a fluoride oxalate container used for glucose analysis. A follow-up contrast-enhanced CT angiogram did not demonstrate any abnormalities. It transpired that excess CSF had been collected into a fluoride oxalate container. This had subsequently been decanted into a plain container for microbiological analysis. Correct specimen collection should be emphasised when teaching lumbar puncture technique. PMID:26139652

Hafnium(IV) complexation with oxalate at variable temperatures

Energy Technology Data Exchange (ETDEWEB)

Friend, Mitchell T.; Wall, Nathalie A. [Washington State Univ., Pullmanm, WA (United States). Dept. of Chemistry

2017-08-01

Appropriate management of fission products in the reprocessing of spent nuclear fuel (SNF) is crucial in developing advanced reprocessing schemes. The addition of aqueous phase complexing agents can prevent the co-extraction of these fission products. A solvent extraction technique was used to study the complexation of Hf(IV) - an analog to fission product Zr(IV) - with oxalate at 15, 25, and 35 C in 1 M HClO{sub 4} utilizing a {sup 175+181}Hf radiotracer. The mechanism of the solvent extraction system of 10{sup -5} M Hf(IV) in 1 M HClO{sub 4} to thenoyltrifluoroacetone (TTA) in toluene demonstrated a 4{sup th}-power dependence in both TTA and H{sup +}, with Hf(TTA){sub 4} the only extractable species. The equilibrium constant for the extraction of Hf(TTA){sub 4} was determined to be log K{sub ex}=7.67±0.07 (25±1 C, 1 M HClO{sub 4}). The addition of oxalate to the aqueous phase decreased the distribution ratio, indicating aqueous Hf(IV)-oxalate complex formation. Polynomial fits to the distribution data identified the formation of Hf(ox){sup 2+} and Hf(ox){sub 2(aq)} and their stability constants were measured at 15, 25, and 35 C in 1 M HClO{sub 4}. van't Hoff analysis was used to calculate Δ{sub r}G, Δ{sub r}H, and Δ{sub r}S for these species. Stability constants were observed to increase at higher temperature, an indication that Hf(IV)-oxalate complexation is endothermic and driven by entropy.

Dissolution of oxalate precipitate and destruction of oxalate ion by hydrogen peroxide in nitric acid solution

International Nuclear Information System (INIS)

Kim, Eung-Ho; Chung, Dong-Yong; Park, Jin-Ho; Yoo, Jae-Hyung

2000-01-01

This study aims at developing an oxalate precipitation process, which is applicable to a partitioning of long-lived radionuclides from the high-level radioactive liquid waste. In order to achieve this, a study for decomposition-reaction of oxalic acid by hydrogen peroxide was first carried out. The decomposition rates of H 2 O 2 and oxalic acid increased with an increase of nitric acid concentration, and especially those decomposition rates steeply increased at more than 2 M HNO 3 . Based on this result, the decomposition kinetics of H 2 O 2 and oxalic acid were suggested in this work. Then, the dissolution of oxalate precipitate and the destruction of oxalate ion in the solution were examined. Oxalate precipitates were prepared by adding oxalic acid into a simulated radioactive waste containing 8 metallic elements. The precipitates obtained thereby were dissolved in various nitric acid concentrations and reacted with H 2 O 2 at 90degC. When the oxalates were completely dissolved, most of the oxalates were decomposed by adding H 2 O 2 , but in a slurry state the decomposition yield of the oxalate decreased with an increase of the slurry density in the solution. Such phenomenon was considered to be due to a catalytic decomposition of H 2 O 2 on a solid surface of oxalate and the decomposition mechanism was explained by a charge transfer from a surface of oxalate solid to H 2 O 2 , producing OH radicals which can destruct H 2 O 2 explosively. Accordingly, the experimental condition for the decomposition of the oxalate precipitates was found to be most favorable at 3 M HNO 3 under the initial concentrations of 0.2 M oxalate and 1 M H 2 O 2 . At 3M HNO 3 , oxalate precipitates could be safely and completely dissolved, and almost decomposed. Additionally, it was observed that the presence of ferric ion in the solution largely affects the decomposition rate of H 2 O 2 . This could be explained by a chain reaction of hydrogen peroxide with ferric ion in the solution

[Features of calcium crystals and calcium components in 54 plant species in salinized habitats of Tianjin].

Science.gov (United States)

Xu, Jing-Jing; Ci, Hua-Cong; He, Xing-Dong; Xue, Ping-Ping; Zhao, Xue-Lai; Guo, Jian-Tan; Gao, Yu-Bao

2012-05-01

Plant calcium (Ca) is composed of dissociated Ca2+ and easily soluble, slightly soluble, and hard soluble combined Ca salts. The hard soluble Ca salts can often engender Ca crystals. To understand the Ca status in different growth form plants in salinized habitats, 54 plant species were sampled from the salinized habitats in Tianjin, with the Ca crystals examined by microscope and the Ca components determined by sequential fractionation procedure. More Ca crystals were found in 38 of the 54 plant species. In 37 of the 38 plant species, drusy and prismatic Ca oxalate crystals dominated, whereas the cystolith of Ca carbonate crystal only appeared in the leaves of Ficus carica of Moraceae. The statistics according to growth form suggested that deciduous arbors and shrubs had more Ca oxalate crystal, liana had lesser Ca oxalate crystal, and herbs and evergreen arbors had no Ca oxalate crystal. From arbor, shrub, liana to herb, the concentration of HCl-soluble Ca decreased gradually, while that of water soluble Ca was in adverse. The concentration of water soluble Ca in herbs was significantly higher than that in arbors and shrubs. This study showed that in salinized habitats, plant Ca crystals and Ca components differed with plant growth form, and the Ca oxalate in deciduous arbors and shrubs played an important role in withstanding salt stress.

Vibrational studies in aqueous solutions. Part II. The acid oxalate ion and oxalic acid

Science.gov (United States)

Shippey, T. A.

1980-08-01

Assignments for oxalic acid in solution are re-examined. A detailed assignment of the IR and Raman spectra of the acid oxalate ion is presented for the first time. Raman spectroscopy is used to study the first ionization of oxalic acid.

Crystal structure of a mixed-ligand terbium(III coordination polymer containing oxalate and formate ligands, having a three-dimensional fcu topology

Directory of Open Access Journals (Sweden)

Chainok Kittipong

2016-01-01

Full Text Available The title compound, poly[(μ3-formato(μ4-oxalatoterbium(III], [Tb(CHO2(C2O4]n, is a three-dimensional coordination polymer, and is isotypic with the LaIII, CeIII and SmIII analogues. The asymmetric unit contains one TbIII ion, one formate anion (CHO2− and half of an oxalate anion (C2O42−, the latter being completed by application of inversion symmetry. The TbIII ion is nine-coordinated in a distorted tricapped trigonal–prismatic manner by two chelating carboxylate groups from two C2O42− ligands, two carboxylate oxygen atoms from another two C2O42− ligands and three oxygen atoms from three CHO2− ligands, with the Tb—O bond lengths and the O—Tb—O bond angles ranging from 2.4165 (19 to 2.478 (3 Å and 64.53 (6 to 144.49 (4°, respectively. The CHO2− and C2O42− anions adopt μ3-bridging and μ4-chelating-bridging coordination modes, respectively, linking adjacent TbIII ions into a three-dimensional 12-connected fcu topology with point symbol (324.436.56. The title compound exhibits thermal stability up to 623 K, and also displays strong green photoluminescence in the solid state at room temperature.

Thermodynamic analysis of stability in iron removal from kaolin by using oxalic acid

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C. Ocampo-López

2013-06-01

Full Text Available The graphical representation of global stability for a system, or Pourbaix diagram, was constructed to perform a thermodynamic study of iron removal from kaolin using oxalic acid as an oxidant. To do this the free energies of formation of the oxalate complex of the system were calculated, and it was found that the more stable specie is Fe(C2O43-3, with a calculated free energy of formation of -3753.88 kcal/mol. Thermodynamic stability functions were estimated for the system as a function of pH and Eh known as potential of oxide reduction. It was built a global stability diagram for the removal system; it showed that the specie trioxalate Fe(C2O43-3 is the only oxalate in equilibrium with other compounds associated with the removal of iron in kaolin.

Variation in oxalate and oxalate decarboxylase production by six species of brown and white rot fungi

DEFF Research Database (Denmark)

Hastrup, Anne Christine Steenkjær; Oliver, Jason; Howell, Caitlin

  Oxalic acid (C2O4H2), the strongest of the organic acids is produced by both brown and white rot decay fungi and has been connected to various aspects of brown- and white rot decay including the Fenton reaction (Green and Highley, 1997; Munir et al.,2001). Oxalic acid is secreted into the wood...... cell lumen where it quickly dissociates into hydrogen ions and oxalate, resulting in a pH decrease of the environment, and oxalate-cation complexes. Generally, brown rot fungi accumulate larger quantities of oxalic acid in the wood than white rot fungi. The amount of oxalic acid has been shown to vary...... of formic acid and CO2 (Makela et al., 2002). So far only a few species of brown rot fungi have been shown to accumulate this enzyme (Micales, 1995, Howell and Jellison, 2006).   The purpose of this study was to investigate the variation in the levels of soluble oxalate and total oxalate, in correlation...

Manganese oxalate nanorods as ballistic modifier for composite solid propellants

Energy Technology Data Exchange (ETDEWEB)

Singh, Supriya [Department of Chemistry, DDU Gorakhpur University, Gorakhpur 273009, U.P. (India); Chawla, Mohit [School of Basic Sciences, Indian Institute of Technology Mandi, Mandi 175005, H.P. (India); Siril, Prem Felix, E-mail: prem@iitmandi.ac.in [School of Basic Sciences, Indian Institute of Technology Mandi, Mandi 175005, H.P. (India); Singh, Gurdip [Department of Chemistry, DDU Gorakhpur University, Gorakhpur 273009, U.P. (India)

2014-12-10

Highlights: • Manganese oxalate nanorods were prepared using mild thermal precipitation and aging. • The nanorods were found to be efficient ballistic modifier for solid propellants. • The nanorods sensitized the thermolysis of ammonium perchlorate. • Controlled thermal decomposition of nanorods yielded manganese oxide nanoparticles. • MnO nanoparticles formed insitu in the condensed phase enhance the burning rates. - Abstract: Rod-shaped nanostructures of manganese oxalate (MnC{sub 2}O{sub 4}) were synthesized via mild thermal precipitation and aging process. Chemical composition of the MnC{sub 2}O{sub 4} nanorods was confirmed using Fourier transform infra-red (FTIR) spectroscopy and energy dispersive X-ray spectroscopy (EDS). X-ray diffraction (XRD) and selected area electron diffraction (SAED) studies revealed the crystal structure. Field emission scanning electron microscopy (FE-SEM) imaging and high resolution transmission electron microscopy (HR-TEM) were employed to study the structural features of the nanorods. The MnC{sub 2}O{sub 4} nanorods were found to be efficient ballistic modifier for the burning rate enhancement of composite solid propellants (CSPs). Thermal analysis using TGA-DSC showed that MnC{sub 2}O{sub 4} nanorods sensitized the thermal decomposition of ammonium perchlorate (AP) and the CSPs. Controlled thermal decomposition of the MnC{sub 2}O{sub 4} nanorods resulted in the formation of managanese oxide nanoparticles with mesoporosity. A plausible mechanism for the burning rate enhancement using MnC{sub 2}O{sub 4} nanorods was proposed.

Increased dietary long-chain polyunsaturated fatty acids alter serum fatty acid concentrations and lower risk of urine stone formation in cats.

Directory of Open Access Journals (Sweden)

Jean A Hall

Full Text Available The lifespan of cats with non-obstructive kidney stones is shortened compared with healthy cats indicating a need to reduce stone formation and minimize chronic kidney disease. The purpose of this study was to investigate the effects of increasing dietary polyunsaturated fatty acids (PUFA on urine characteristics. Domestic-short-hair cats (n = 12; mean age 5.6 years were randomized into two groups and fed one of two dry-cat foods in a cross-over study design. For one week before study initiation, all cats consumed control food that contained 0.07% arachidonic acid (AA, but no eicosapentaenoic acid (EPA or docosahexaenoic acid (DHA. Group 1 continued eating control food for 56 days. Group 2 was fed test food for 56 days, which was control food plus fish oil and high-AA oil. Test food contained 0.17% AA, 0.09% EPA and 0.18% DHA. After 56 days, cats were fed the opposite food for another 56 days. At baseline and after each feeding period, serum was analyzed for fatty acid concentrations, and urine for specific gravity, calcium concentration, relative-super-saturation for struvite crystals, and a calcium-oxalate-titrimetric test was performed. After consuming test food, cats had increased (all P<0.001 serum concentrations of EPA (173%, DHA (61%, and AA (35%; decreased urine specific gravity (P = 0.02; decreased urine calcium concentration (P = 0.06; decreased relative-super-saturation for struvite crystals (P = 0.03; and increased resistance to oxalate crystal formation (P = 0.06 compared with cats consuming control food. Oxalate crystal formation was correlated with serum calcium concentration (r = 0.41; P<0.01. These data show benefits for reducing urine stone formation in cats by increasing dietary PUFA.

Behaviour of Pu-IV with various ion exchangers in solutions containing nitric acid and oxalates

International Nuclear Information System (INIS)

Walter, E.; Ali, S.A.

1982-02-01

The distribution of Pu-IV on the ion exchangers Dowex 50W-X8, Dowex 1-X8 und Dowex Chelating Resin Al-X8 in the presence of various concentrations of nitric acid and oxalate were investigated. The results indicate that nitric acid and oxalic acid influence each other during complexation of Pu-IV with oxalate ions solutions containing nitric acid it is not possible to neglect the formation of Pu-IV nitrate complexes. The complex Pu(IV) (C 2 O 4 ) 3 2 - only is formed in solutions containing low nitric acid and high oxalic acid concentrations. The separation of Pu-IV in Dowex Chelating Resin from nitric acid solution in the presence of higher oxalate concentrations is possible, provided that the nitric acid concentration is lower than 0.25 molar [fr

Dynamic process model of a plutonium oxalate precipitator

International Nuclear Information System (INIS)

Borgonovi, G.M.; Hammelman, J.E.; Miller, C.L.

1980-01-01

A dynamic model of a plutonium oxalate precipitator is developed to provide a means of predicting plutonium inventory on a continuous basis. The model is based on state-of-the-art crystallization equations, which describe nucleation and growth phenomena. The model parameters were obtained through the use of batch experimental data. The model has been used to study the approach to steady state, to investigate the response to input transients, and to simulate the control of the precipitation process. 12 refs

Structural variability in neptunium(V) oxalate compounds: synthesis and structural characterization of Na2NpO2(C2O4)OH.H2O.

Science.gov (United States)

Bean, Amanda C; Garcia, Eduardo; Scott, Brian L; Runde, Wolfgang

2004-10-04

Reaction of a (237)Np(V) stock solution in the presence of oxalic acid, calcium chloride, and sodium hydroxide under hydrothermal conditions produces single crystals of a neptunium(V) oxalate, Na(2)NpO(2)(C(2)O(4))OH.H(2)O. The structure consists of one-dimensional chains running down the a axis and is the first example of a neptunium(V) oxalate compound containing hydroxide anions.

Hydrothermal synthesis of two layered indium oxalates with 12-membered apertures

International Nuclear Information System (INIS)

Chen Zhenxia; Zhou Yaming; Weng Linhong; Zhang Haoyu; Zhao Dongyuan

2003-01-01

Two layered indium oxalates, In(C 2 O 4 ) 2.5 (C 3 N 2 H 12 )(H 2 O) 3 , I, and In(C 2 O 4 ) 1.5 (H 2 O) 3 , II, have been hydrothermally synthesized. In I, the linkage between indium and oxalate units gives rise to a sheet with a rectangular 12-membered aperture (six indium atoms and six oxalate units). Indium atom of II has an unusual pentagonal bipyramidal coordination arrangement. The connectivity between indium and oxalate units forms a neutral puckered layer with 12- (along a-axis) and eight-membered (along b-axis) apertures. Crystal data for these two indium oxalates are as follows: I, triclinic, space group: P-1 (No. 2), a=8.725(3) A, b=9.170(3) A, c=9.901(3) A, α=98.101(4) deg. , β=97.068(4) deg. , γ=102.403(4) deg. , V=756.3(4) A 3 , Z=2, M=463.0(5), ρ calc =2.042 g/cm 3 , R 1 =0.0377, wR 2 =0.0834. II, monoclinic, space group: P2 1 /c (No. 14), a=10.203(5) A, b=6.638(1) A, c=11.152(7) A, β=95.649(4) deg. , V=751.7(4)A 3 , Z=4, M=300.9(0), ρ calc =2.659 g/cm 3 , R 1 =0.0229, wR 2 =0.0488. TG analyses indicate the water molecules of I can be removed at 150 deg. C. The dehydrated product retains structural integrity

Effect of different brewing times on soluble oxalate content of loose-packed black teas and tea bags.

Science.gov (United States)

Mahdavi, Reza; Lotfi Yagin, Neda; Liebman, Michael; Nikniaz, Zeinab

2013-02-01

Because of the postulated role of increased dietary oxalate intake in calcium oxalate stone formation, the effect of different brewing times on soluble oxalate contents of loose-packed black tea and tea bags was studied. The oxalate content of 25 different samples of loose-packed black teas after brewing at 5, 10, 15, 30, and 60 min and of ten brands of tea bags after infusion for 1, 2, 3, 4, and 5 min was measured by enzymatic assay. The oxalate concentration resulting from different brewing times ranged from 4.3 to 6.2 mg/240 ml for loose-packed black teas and from 2.7 to 4.8 mg/240 ml for tea bags. There was a stepwise increase in oxalate concentration associated with increased brewing times.

Oxalate: Effect on calcium absorbability

International Nuclear Information System (INIS)

Heaney, R.P.; Weaver, C.M.

1989-01-01

Absorption of calcium from intrinsically labeled Ca oxalate was measured in 18 normal women and compared with absorption of Ca from milk in these same subjects, both when the test substances were ingested in separate meals and when ingested together. Fractional Ca absorption from oxalate averaged 0.100 +/- 0.043 when ingested alone and 0.140 +/- 0.063 when ingested together with milk. Absorption was, as expected, substantially lower than absorption from milk (0.358 +/- 0.113). Nevertheless Ca oxalate absorbability in these women was higher than we had previously found for spinach Ca. When milk and Ca oxalate were ingested together, there was no interference of oxalate in milk Ca absorption and no evidence of tracer exchange between the two labeled Ca species

The bioavailability of oxalate from Oca (Oxalis tuberosa).

Science.gov (United States)

Albihn, P B; Savage, G P

2001-08-01

It is believed that soluble oxalate has higher bioavailability than insoluble oxalate. Oca (Oxalis tuberosa) is moderately high in oxalate and contains oxalate in soluble form only. We estimated the bioavailability of oxalate in oca based on the urinary excretion of oxalate after oxalate loading with oca to estimate the bioavailability of oxalate in oca. We also clarified whether bioavailability differs in various oxalate loads from the same food source and studied the effect of an additional calcium source on the bioavailability of oxalate from oca. Four men and 4 women ingested 50, 100 and 150 gm. oca as well as 100 gm. oca with 100 gm. sour cream. Oxalate was measured in a 6-hour urine sample from each volunteer. The mean bioavailability of oxalate from oca plus or minus standard deviation was 1.44% +/- 1.31% during the 6-hour period after intake. There was no significant difference in oxalate bioavailability among oxalate intake levels in this study, although oca consumption with sour cream significantly decreased the uptake of oxalate (p oca appears to be similar to that in spinach. However, bioavailability varies among individuals and depends on other constituents of a combined meal.

Internalization of Calcium Oxalate Calculi Developed in Narrow Cavities

Directory of Open Access Journals (Sweden)

Fèlix Grases

2014-03-01

Full Text Available We describe the case of a patient with calcium oxalate monohydrate and calcium oxalate dihydrate calculi occluded in cavities. All those calculi were located inside narrow cavities covered with a thin epithelium that permits their visualization. Urinary biochemical analysis showed high calciuria, not hypercalciuria, hypocitraturia, and a ratio [calcium]/[citrate] >0.33. The existence of cavities of very low urodynamic efficacy was decisive in the formation of such calculi. It is important to emphasize that we observed a thin epithelium covering such cavities, demonstrating that this epithelium may be formed after the development of the calculi through a re-epithelialization process.

Precipitation of plutonium (III) oxalate and calcination to plutonium oxide

International Nuclear Information System (INIS)

Esteban, A.; Orosco, E.H.; Cassaniti, P.; Greco, L.; Adelfang, P.

1989-01-01

The plutonium based fuel fabrication requires the conversion of the plutonium nitrate solution from nuclear fuel reprocessing into pure PuO2. The conversion method based on the precipitation of plutonium (III) oxalate and subsequent calcination has been studied in detail. In this procedure, plutonium (III) oxalate is precipitated, at room temperature, by the slow addition of 1M oxalic acid to the feed solution, containing from 5-100 g/l of plutonium in 1M nitric acid. Before precipitation, the plutonium is adjusted to trivalent state by addition of 1M ascorbic acid in the presence of an oxidation inhibitor such as hydrazine. Finally, the precipitate is calcinated at 700 deg C to obtain PuO2. A flowsheet is proposed in this paper including: a) A study about the conditions to adjust the plutonium valence. b) Solubility data of plutonium (III) oxalate and measurements of plutonium losses to the filtrate and wash solution. c) Characterization of the obtained products. Plutonium (III) oxalate has several potential advantages over similar conversion processes. These include: 1) Formation of small particle sizes powder with good pellets fabrication characteristics. 2) The process is rather insensitive to most process variables, except nitric acid concentration. 3) Ambient temperature operations. 4) The losses of plutonium to the filtrate are less than in other conversion processes. (Author) [es

Calcium oxalate crystals induces tight junction disruption in distal renal tubular epithelial cells by activating ROS/Akt/p38 MAPK signaling pathway.

Science.gov (United States)

Yu, Lei; Gan, Xiuguo; Liu, Xukun; An, Ruihua

2017-11-01

Tight junction plays important roles in regulating paracellular transports and maintaining cell polarity. Calcium oxalate monohydrate (COM) crystals, the major crystalline composition of kidney stones, have been demonstrated to be able to cause tight junction disruption to accelerate renal cell injury. However, the cellular signaling involved in COM crystal-induced tight junction disruption remains largely to be investigated. In the present study, we proved that COM crystals induced tight junction disruption by activating ROS/Akt/p38 MAPK pathway. Treating Madin-Darby canine kidney (MDCK) cells with COM crystals induced a substantial increasing of ROS generation and activation of Akt that triggered subsequential activation of ASK1 and p38 mitogen-activated protein kinase (MAPK). Western blot revealed a significantly decreased expression of ZO-1 and occludin, two important structural proteins of tight junction. Besides, redistribution and dissociation of ZO-1 were observed by COM crystals treatment. Inhibition of ROS by N-acetyl-l-cysteine (NAC) attenuated the activation of Akt, ASK1, p38 MAPK, and down-regulation of ZO-1 and occludin. The redistribution and dissociation of ZO-1 were also alleviated by NAC treatment. These results indicated that ROS were involved in the regulation of tight junction disruption induced by COM crystals. In addition, the down-regulation of ZO-1 and occludin, the phosphorylation of ASK1 and p38 MAPK were also attenuated by MK-2206, an inhibitor of Akt kinase, implying Akt was involved in the disruption of tight junction upstream of p38 MAPK. Thus, these results suggested that ROS-Akt-p38 MAPK signaling pathway was activated in COM crystal-induced disruption of tight junction in MDCK cells.

Synthesis and characterization of polymorphs of photoluminescent Eu(III)-(2,5-furandicarboxylic acid, oxalic acid) MOFs

International Nuclear Information System (INIS)

Shi, Fa-Nian; Ananias, Duarte; Yang, Ting-Hai; Rocha, João

2013-01-01

A novel metal organic framework (MOF) formulated as [Eu(H 2 O) 2 (fdc)(ox) 0.5 ·(H 2 O)] n (1, fdc 2− =2,5-furandicarboxylate, ox 2− =oxalate), was hydrothermally synthesized via in situ ox 2− generation from the partial decomposition of the fdc 2− ligand. This material crystallizes in the monoclinic space group C2/c, unit cell parameters of 1: a=16.7570(10), b=10.5708(7), c=13.5348(14) Å, β=116.917(2)° (Z=8), and exhibits a three-dimensional (3D)-porous framework, with guest water molecules residing in the channel linking all other ligands (H 2 O, ox 2− and fdc 2− ) via hydrogen bonding interactions. Compound 2 is a polymorph of 1 crystallizing in monoclinic P21/c space group. The photoluminescence properties of 1 and 2 were studied at room temperature. The spectra show the typical Eu 3+ red emission and the differences observed reflects the slightly different structures of these polymorphs. - Graphical abstract: Exploring metal organic framework polymorphism in the system Eu(H 2 O) 2 (fdc)(ox) 0.5 ·(H 2 O)] n (fdc 2− =2,5-furandicarboxylate, ox 2− =oxalate) for tuning light emission. Display Omitted - Highlights: • Synthesis of Eu(III)-(2,5-furandicarboxylic acid, oxalic acid) MOF polymorphs. • Detailed single-crystal study of polymorphs including hydrogen-bonding networks. • Photoluminescence spectroscopy show subtle differences light emission properties

Formation and electrical transport properties of pentacene nanorod crystal

International Nuclear Information System (INIS)

Akai-Kasaya, M; Ohmori, C; Kawanishi, T; Nashiki, M; Saito, A; Kuwahara, Y; Aono, M

2010-01-01

The monophasic formation of an uncharted pentacene crystal, the pentacene nanorod, has been investigated. The restricted formation of the pentacene nanorod on a bare mica surface reveals a peculiar surface catalytic crystal growth mode of the pentacene. We demonstrated the charge transport measurements through a single pentacene nanorod and analyzed the data using a periodic hopping conduction model. The results revealed that the pentacene nanorod has a periodic conductive node within their one-dimensional crystal.

Formation and electrical transport properties of pentacene nanorod crystal.

Science.gov (United States)

Akai-Kasaya, M; Ohmori, C; Kawanishi, T; Nashiki, M; Saito, A; Aono, M; Kuwahara, Y

2010-09-10

The monophasic formation of an uncharted pentacene crystal, the pentacene nanorod, has been investigated. The restricted formation of the pentacene nanorod on a bare mica surface reveals a peculiar surface catalytic crystal growth mode of the pentacene. We demonstrated the charge transport measurements through a single pentacene nanorod and analyzed the data using a periodic hopping conduction model. The results revealed that the pentacene nanorod has a periodic conductive node within their one-dimensional crystal.

Decomposition of oxalate precipitates by photochemical reaction

International Nuclear Information System (INIS)

Jae-Hyung Yoo; Eung-Ho Kim

1999-01-01

A photo-radiation method was applied to decompose oxalate precipitates so that it can be dissolved into dilute nitric acid. This work has been studied as a part of partitioning of minor actinides. Minor actinides can be recovered from high-level wastes as oxalate precipitates, but they tend to be coprecipitated together with lanthanide oxalates. This requires another partitioning step for mutual separation of actinide and lanthanide groups. In this study, therefore, some experimental work of photochemical decomposition of oxalate was carried out to prove its feasibility as a step of partitioning process. The decomposition of oxalic acid in the presence of nitric acid was performed in advance in order to understand the mechanistic behaviour of oxalate destruction, and then the decomposition of neodymium oxalate, which was chosen as a stand-in compound representing minor actinide and lanthanide oxalates, was examined. The decomposition rate of neodymium oxalate was found as 0.003 mole/hr at the conditions of 0.5 M HNO 3 and room temperature when a mercury lamp was used as a light source. (author)

Effects of low molecular weight organic acids on the immobilization of aqueous Pb(II) using phosphate rock and different crystallized hydroxyapatite.

Science.gov (United States)

Wei, Wei; Cui, Jing; Wei, Zhenggui

2014-06-01

Understanding the effects of low molecular weight organic acids (LMWOAs) on the transformation of Pb(II) to geochemically stable pyromorphite (PY) by apatite materials (AMs), has considerable benefits for risk assessment and remediation strategies for contaminated water and soil. In this study, we systematically investigated the immobilization of Pb(II) from aqueous solution by natural phosphate rock (PR) and different crystallized hydroxyapatite (HAp) in the absence and presence of LMWOAs (oxalic, malic and citric acids). The results indicated that the effectiveness of PR and HAp in immobilizing Pb(II) followed in descending order by HAp2 (the poorly crystallized HAp), HAp1 (the well crystallized HAp) and PR, regardlessof the presence of LMWOAs. The presence of malic and citric acids significantly decreased the immobilizationefficiency of Pb(II) by HAp1 and PR, clarifying the lower adsorption affinities of Pb(II)-organic acid complexes on HAp1 and PR rather than Pb(II) ion. On thecontrary, oxalic acid could markedly enhance the removal of Pb(II) from aqueous solution by HAp1 and PR through the formation of lead oxalate, which was confirmed by FT-IR and XRDanalysis. Results also showed that LMWOAs had little promoting or inhibiting effect on the immobilization of Pb(II) by HAp2. This study suggested that the ubiquity of LMWOAs in natural environments could retard the transformation efficiency of Pb(II) to PY by AMs, especiallyin thepresenceof oxalic acid, and the poorly crystallized HAp2 had great potential to remediate Pb(II)-contaminated water and soil due to its insusceptibility to LMWOAs. Copyright © 2013 Elsevier Ltd. All rights reserved.

In vivo oxalate degradation by liposome encapsulated oxalate oxidase in rat model of hyperoxaluria

Directory of Open Access Journals (Sweden)

Tulika Dahiya

2013-01-01

Interpretation & conclusions: EMA-oxalate oxidase encapsulated liposome caused oxalate degradation in experimental hyperoxaluria indicating that the enzyme could be used as a therapeutic agent in hyperoxaluria leading to urinary stones.

Tetra­kis(aceto­nitrile)copper(I) hydrogen oxalate–oxalic acid–aceto­nitrile (1/0.5/0.5)

Science.gov (United States)

Royappa, A. Timothy; Stepherson, Jacob R.; Vu, Oliver D.; Royappa, Andrew D.; Stern, Charlotte L.; Müller, Peter

2013-01-01

In the title compound, [Cu(CH3CN)4](C2HO4)·0.5C2H2O4·0.5CH3CN, the CuI ion is coordinated by the N atoms of four aceto­nitrile ligands in a slightly distorted tetra­hedral environment. The oxalic acid mol­ecule lies across an inversion center. The aceto­nitrile solvent mol­ecule is disordered across an inversion center and was refined with half occupancy. In the crystal, the hydrogen oxalate anions and oxalic acid mol­ecules are linked via O—H⋯O hydrogen bonds, forming chains along [010]. PMID:24098175

Thermal behaviour of iron (II) oxalate dihydrate in the atmosphere of its conversion gases

Czech Academy of Sciences Publication Activity Database

Heřmánek, M.; Zbořil, R.; Mašláň, M.; Machala, L.; Schneeweiss, Oldřich

2006-01-01

Roč. 16, č. 13 (2006), s. 1273-1280 ISSN 0959-9428 R&D Projects: GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : hydrous ferrous oxalate * oxide nanoparticles * crystal-structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.287, year: 2006

Recovery Ce from Ce - TBP Used Oxalic Acid

International Nuclear Information System (INIS)

Purwani, MV; Subagiono, R.; Suyanti

2007-01-01

Recovery or stripping Ce from Ce - TBP product of monazite sand used oxalic acid. Ce - TBP as organic phase and oxalic acid as aqueous phase and as strong precipitant compound to precipitate metal element. The stripping product as Ce - oxalic precipitate. The influence parameter were percentage of oxalic acid, volume ratio of Ce-TBP with oxalic acid, time and rate of stripping. At stripping of 25 ml Ce - TBP used oxalic acid, the optimum condition were achieve at using 5% oxalic acid, volume ratio of Ce - TBP : 5% oxalic acid = 1 : 1, time of stripping 7.5 minute and rate of stripping 150 rpm. At the optimum condition was obtained the recovery efficiency was 100%. (author)

Specificity in calcium oxalate adherence to papillary epithelial cells in culture

International Nuclear Information System (INIS)

Riese, R.J.; Riese, J.W.; Kleinman, J.G.; Wiessner, J.H.; Mandel, G.S.; Mandel, N.S.

1988-01-01

Attachment of microcystallites to cellular membranes may be an important component of the pathophysiology of many diseases including urolithiasis. This study attempts to characterize the interaction of calcium oxalate (CaOx) crystals and apatite (AP) crystals with renal papillary collecting tubule (RPCT) cells in primary culture. Primary cultures of RPCT cells showed the characteristic monolayer growth with sporadically interspersed clumped cells. Cultures were incubated with [ 14 C]CaOx crystals, and the crystals that bound were quantified by microscopy and adherent radioactivity. Per unit of cross-sectional area, 32 times more CaOx crystals were bound to the clumps than to the monolayer. CaOx adherence demonstrated concentration-dependent saturation with a β value (fraction of cell culture area binding CaOx crystals) of 0.179 and a 1/α ox value of 287 μg/cm 2 . On incubation with AP crystals, CaOx binding demonstrated concentration-dependent inhibition with a 1/α AP value of 93 μg/cm 2 . Microcystallite adherence to RPCT cells demonstrates selectivity for cellular clumps, saturation, and inhibition. These features suggest specific binding

X-ray fluorescence analysis of neodymium oxide/oxalate for rare earth impurities

International Nuclear Information System (INIS)

Chandola, L.C.; Mohile, A.N.

1977-01-01

An X-ray fluorescence method for the determination of cesium, praseodymium, samarium, europium and gadolinium in pure neodymium oxide and oxalate is described. The oxide sample is converted to oxalate and mixed with a binder (boric acid) to obtain a pressed circular pellet. The amount of sample needed for analysis is reduced by making use of the double layer pellet technique. A tungsten target X-ray tube is employed to irradiate the sample and a Philips PW 1220 semiautomatic X-ray spectrometer with a LiF (200) crystal is used to analyse the fluorescent X-rays. The minimum determination limit is 0.01 percent for all rare earths determined except for europium for which the limit is 0.005 percent. Three sigma detection limits have been calculated. (author)

In-cloud oxalate formation in the global troposphere: A 3-D modeling study

NARCIS (Netherlands)

Myriokefalitakis, S.; Tsigaridis, K.; Mihalopoulos, N.; Sciare, J.; Nenes, A.; Kawamura, K.; Segers, A.; Kanakidou, M.

2011-01-01

Organic acids attract increasing attention as contributors to atmospheric acidity, secondary organic aerosol mass and aerosol hygroscopicity. Oxalic acid is globally the most abundant dicarboxylic acid, formed via chemical oxidation of gas-phase precursors in the aqueous phase of aerosols and

High variability of the heterogeneous ice nucleation potential of oxalic acid dihydrate and sodium oxalate

OpenAIRE

R. Wagner; O. Möhler; H. Saathoff; M. Schnaiter; T. Leisner

2010-01-01

The heterogeneous ice nucleation potential of airborne oxalic acid dihydrate and sodium oxalate particles in the deposition and condensation mode has been investigated by controlled expansion cooling cycles in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at temperatures between 244 and 228 K. Previous laboratory studies have highlighted the particular role of oxalic acid dihydrate as the only species amongst a variety of other investigated dicarboxylic acids to ...

The comparability of oxalate excretion and oxalate:creatinine ratio in the investigation of primary hyperoxaluria: review of data from a referral centre.

Science.gov (United States)

Clifford-Mobley, Oliver; Tims, Christopher; Rumsby, Gill

2015-01-01

Urine oxalate measurement is an important investigation in the evaluation of renal stone disease. Primary hyperoxaluria (PH) is a rare inherited metabolic disease characterised by persistently elevated urine oxalate, but the diagnosis may be missed in adults until renal failure has developed. Urine oxalate results were reviewed to compare oxalate:creatinine ratio and oxalate excretion, and to estimate the potential numbers of undiagnosed PH. Urine oxalate results from August 2011 to April 2013 were reviewed. Oxalate excretion and oxalate:creatinine ratio were evaluated for 24 h collections and ratio alone for spot urine samples. Oxalate:creatinine ratio and oxalate excretion were moderately correlated (R=0.63) in 24-h urine collections from patients aged 18 years and above. Sex-related differences were found requiring implementation of male and female reference ranges for oxalate:creatinine ratio. Of samples with both ratio and excretion above the reference range, 7% came from patients with confirmed PH. There were 24 patients with grossly elevated urine oxalate who had not been evaluated for PH. Oxalate:creatinine ratio and oxalate excretion were discordant in many patients, which is likely to be a result of intra-individual variation in creatinine output and imprecision in the collection itself. Some PH patients had urine oxalate within the reference range on occasion, and therefore it is not possible to exclude PH on the finding of a single normal result. A significant number of individuals had urine oxalate results well above the reference range who potentially have undiagnosed PH and are consequently at risk of renal failure. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Effects of Orthosiphon grandiflorus, Hibiscus sabdariffa and Phyllanthus amarus extracts on risk factors for urinary calcium oxalate stones in rats.

Science.gov (United States)

Woottisin, Surachet; Hossain, Rayhan Zubair; Yachantha, Chatchai; Sriboonlue, Pote; Ogawa, Yoshihide; Saito, Seiichi

2011-01-01

We evaluated the antilithic effect of Orthosiphon grandiflorus, Hibiscus sabdariffa and Phyllanthus amarus extracts on known risk factors for calcium oxalate stones in rats. We divided 30 male Wistar rats into 5 equal groups. Controls were fed a standard diet and the remaining groups received a 3% glycolate diet for 4 weeks to induce hyperoxaluria. One glycolate fed group served as the untreated group and the others were given oral extracts of Orthosiphon grandiflorus, Hibiscus sabdariffa or Phyllanthus amarus at a dose of 3.5 mg daily. We collected 24-hour urine and blood samples. Kidneys were harvested for histological examination. We measured the renal tissue content of calcium and oxalate. The Hibiscus sabdariffa group showed significantly decreased serum oxalate and glycolate, and higher oxalate urinary excretion. The Phyllanthus amarus group showed significantly increased urinary citrate vs the untreated group. Histological examination revealed less CaOx crystal deposition in the kidneys of Hibiscus sabdariffa and Phyllanthus amarus treated rats than in untreated rats. Those rats also had significantly lower renal tissue calcium content than untreated rats. All parameters in the Orthosiphon grandiflorus treated group were comparable to those in the untreated group. Hibiscus sabdariffa and Phyllanthus amarus decreased calcium crystal deposition in the kidneys. The antilithic effect of Hibiscus sabdariffa may be related to decreased oxalate retention in the kidney and more excretion into urine while that of Phyllanthus amarus may depend on increased urinary citrate. In contrast, administering Orthosiphon grandiflorus had no antilithic effect. Copyright © 2011 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Renal Epithelial Cell Injury Induced by Calcium Oxalate Monohydrate Depends on their Structural Features: Size, Surface, and Crystalline Structure.

Science.gov (United States)

Sun, Xin-Yuan; Ouyang, Jian-Ming; Gan, Qiong-Zhi; Liu, Ai-Jie

2016-11-01

Urinary crystals in normal and kidney stone patients often differ in crystal sizes and surface structures, but the effects of different crystal properties on renal tubular epithelial cells remain unclear. This study aimed to compare the cytotoxicity of micron/nano-calcium oxalate monohydrate (COM) crystals with sizes of 50 nm, 200 nm, 1 μm, 3 μm, and 10 μm to African green monkey renal epithelial (Vero) cells, to reveal the effect of crystal size and surface structure on cell injury, and to investigate the pathological mechanism of calcium oxalate kidney stones. Cell viability, cellular biochemical parameters, and internalized crystal amount in Vero cells were closely associated with the size of COM crystals. At the same concentration (200 μg/mL), COM-1 μm induced the most serious injury to Vero cells and caused the most significant change to cellular biochemical parameters, which were related to the specific porous structure and highest internalized amount in Vero cells. By contrast, COM-50 nm and COM-200 nm crystals lost their small size effect because of serious aggregation and weakened their toxicity to cells. COM-3 μm and COM-10 μm crystals were too large for cells to completely internalize; these crystals also exhibited a low specific surface area and thus weakened their toxicity. The excessive expression of intracellular ROS and reduction of the free-radical scavenger SOD were the main reasons for cell injury and eventually caused necrotic cell death. Crystal size, surface structure, aggregation, and internalization amount were closely related to the cytotoxicity of COM crystals.

Kinetics of uranium (4) oxidation with nitrous acid in the presence of oxalate-ions in nitric and perchloric acid solutions

International Nuclear Information System (INIS)

Nikitenko, S.I.; Astafurova, L.N.

1991-01-01

Kinetics of uranium (4) oxidation with nitrous acid in the presence of oxalate-ions are studied spectrometrically. It is shown that even at small oxalate concentrations a notable effect of tetravalent uranium stabilization is observed relatively to the oxidation with nitrous acid. In case of a significant excess of oxalate-ions the oxidation rate will be considerably slower as a result of the formation of U(4) bisoxalate complex

Surface relief grating formation on a single crystal of 4-(dimethylamino)azobenzene

International Nuclear Information System (INIS)

Nakano, Hideyuki; Tanino, Takahiro; Shirota, Yasuhiko

2005-01-01

Surface relief grating (SRG) formation on an organic single crystal by irradiation with two coherent laser beams has been demonstrated by using 4-(dimethylamino)azobenzene (DAAB). It was found that the SRG formation was greatly depending upon both the coordination of the crystal and the polarization of the writing beams. The dependence of the polarization of writing beams on the SRG formation using the single crystal was found to be quite different from that reported for amorphous polymers and photochromic amorphous molecular materials, suggesting that the mechanism of the SRG formation on the organic crystal is somewhat different from that on amorphous materials

Decomposition of oxalate precipitates by photochemical reaction

International Nuclear Information System (INIS)

Yoo, J.H.; Kim, E.H.

1998-01-01

A photo-radiation method was applied to decompose oxalate precipitates so that it can be dissolved into dilute nitric acid. This work has been studied as a part of partitioning of minor actinides. Minor actinides can be recovered from high-level wastes as oxalate precipitates, but they tend to be coprecipitated together with lanthanide oxalates. This requires another partitioning step for mutual separation of actinide and lanthanide groups. In this study, therefore, the photochemical decomposition mechanism of oxalates in the presence of nitric acid was elucidated by experimental work. The decomposition of oxalates was proved to be dominated by the reaction with hydroxyl radical generated from the nitric acid, rather than with nitrite ion also formed from nitrate ion. The decomposition rate of neodymium oxalate, which was chosen as a stand-in compound representing minor actinide and lanthanide oxalates, was found to be 0.003 M/hr at the conditions of 0.5 M HNO 3 and room temperature when a mercury lamp was used as a light source. (author)

Co-precipitation of plutonium(IV) and americium(III) from nitric acid-oxalic acid solutions with bismuth oxalate

International Nuclear Information System (INIS)

Pius, I.C.; Noronha, D.M.; Chaudhury, Satyajeet

2017-01-01

Co-precipitation of plutonium and americium from nitric acid-oxalic acid solutions with bismuth oxalate has been investigated for the removal of these long lived α-active nuclides from waste solutions. Effect of concentration of bismuth and oxalic acid on the co-precipitation of Pu(IV) from 3 M HNO_3 has been investigated. Similar experiments were also carried out from 3.75 M HNO_3 on co-precipitation of Am(III) to optimize the conditions of precipitation. Strong co-precipitation of Pu(IV) and Am(III) with bismuth oxalate indicate feasibility of treatment of plutonium and americium bearing waste solutions. (author)

A kinetic and ESR investigation of iron(II) oxalate oxidation by hydrogen peroxide and dioxygen as a source of hydroxyl radicals

DEFF Research Database (Denmark)

Park, J S; Wood, P M; Davies, Michael Jonathan

1997-01-01

The reaction of Fe(II) oxalate with hydrogen peroxide and dioxygen was studied for oxalate concentrations up to 20 mM and pH 2-5, under which conditions mono- and bis-oxalate complexes (Fe[II](ox) and Fe[II](ox)2[2-]) and uncomplexed Fe2+ must be considered. The reaction of Fe(II) oxalate...... with hydrogen peroxide (Fe2+ + H2O2 --> Fe3+ + .OH + OH-) was monitored in continuous flow by ESR with t-butanol as a radical trap. The reaction is much faster than for uncomplexed Fe2+ and a rate constant, k = 1 x 10(4) M(-1) s(-1) is deduced for Fe(II)(ox). The reaction of Fe(II) oxalate with dioxygen...... by oxalate. Further ESR studies with DMPO as spin trap reveal that reaction of Fe(II) oxalate with hydrogen peroxide can also lead to formation of the carboxylate radical anion (CO2-), an assignment confirmed by photolysis of Fe(II) oxalate in the presence of DMPO....

Oxalates in oca (New Zealand yam) (Oxalis tuberosa Mol.).

Science.gov (United States)

Ross, A B; Savage, G P; Martin, R J; Vanhanen, L

1999-12-01

Oca (Oxalis tuberosa Mol.) or New Zealand yam, in common with other members of this genus, contains oxalate, an antinutritive factor. Twelve South American and two New Zealand cultivars of oca were analyzed for total and soluble oxalate contents of the tubers. The range of total oxalate levels was 92-221 mg/100 g of fresh weight. Levels of soluble and total oxalate extracted from the tubers were not significantly different, suggesting that no calcium oxalate is formed in the tubers. The oxalate concentrations obtained in this study for oca suggest that previously reported values are too low and that oca is a moderately high oxalate-containing food. This is the first report of a tuber crop containing moderate to high levels of soluble oxalates in the tubers and no insoluble oxalates.

Isolation of oxalic acid tolerating fungi and decipherization of its potential to control Sclerotinia sclerotiorum through oxalate oxidase like protein.

Science.gov (United States)

Yadav, Shivani; Srivastava, Alok K; Singh, Dhanajay P; Arora, Dilip K

2012-11-01

Oxalic acid plays major role in the pathogenesis by Sclerotinia sclerotiorum; it lowers the pH of nearby environment and creates the favorable condition for the infection. In this study we examined the degradation of oxalic acid through oxalate oxidase and biocontrol of Sclerotinia sclerotiorum. A survey was conducted to collect the rhizospheric soil samples from Indo-Gangetic Plains of India to isolate the efficient fungal strains able to tolerate oxalic acid. A total of 120 fungal strains were isolated from root adhering soils of different vegetable crops. Out of 120 strains a total of 80 isolates were able to grow at 10 mM of oxalic acid whereas only 15 isolates were grow at 50 mM of oxalic acid concentration. Then we examined the antagonistic activity of the 15 isolates against Sclerotinia sclerotiorum. These strains potentially inhibit the growth of the test pathogen. A total of three potential strains and two standard cultures of fungi were tested for the oxalate oxidase activity. Strains S7 showed the maximum degradation of oxalic acid (23 %) after 60 min of incubation with fungal extract having oxalate oxidase activity. Microscopic observation and ITS (internally transcribed spacers) sequencing categorized the potential fungal strains into the Aspergillus, Fusarium and Trichoderma. Trichoderma sp. are well studied biocontrol agent and interestingly we also found the oxalate oxidase type activity in these strains which further strengthens the potentiality of these biocontrol agents.

Urinary calcium and oxalate excretion in healthy adult cats are not affected by increasing dietary levels of bone meal in a canned diet.

Directory of Open Access Journals (Sweden)

Nadine Passlack

Full Text Available This study aimed to investigate the impact of dietary calcium (Ca and phosphorus (P, derived from bone meal, on the feline urine composition and the urinary pH, allowing a risk assessment for the formation of calcium oxalate (CaOx uroliths in cats. Eight healthy adult cats received 3 canned diets, containing 12.2 (A, 18.5 (B and 27.0 g Ca/kg dry matter (C and 16.1 (A, 17.6 (B and 21.1 g P/kg dry matter (C. Each diet was fed over 17 days. After a 7 dayś adaptation period, urine and faeces were collected over 2×4 days (with a two-day rest between, and blood samples were taken. Urinary and faecal minerals, urinary oxalate (Ox, the urinary pH and the concentrations of serum Ca, phosphate and parathyroid hormone (PTH were analyzed. Moreover, the urine was microscopically examined for CaOx uroliths. The results demonstrated that increasing levels of dietary Ca led to decreased serum PTH and Ca and increased faecal Ca and P concentrations, but did not affect the urinary Ca or Ox concentrations or the urinary fasting pH. The urinary postprandial pH slightly increased when the diet C was compared to the diet B. No CaOx crystals were detected in the urine of the cats. In conclusion, urinary Ca excretion in cats seems to be widely independent of the dietary Ca levels when Ca is added as bone meal to a typical canned diet, implicating that raw materials with higher contents of bones are of subordinate importance as risk factors for the formation of urinary CaOx crystals.

Synthesis, structure and characterization of two new open-framework gallium phosphite-oxalates of varying dimensionality

International Nuclear Information System (INIS)

Li, Caixia; Huang, Liangliang; Zhou, Mingdong; Xia, Jing; Ma, Hongwei; Zang, Shuliang; Wang, Li

2013-01-01

Using N, N-dimethyl-piperazine as structure directing agent, two new gallium phosphite-oxalates [Ga 2 (HPO 3 ) 2 (H 2 PO 3 ) 2 (C 2 O 4 )](C 6 N 2 H 16 ) (I) and [Ga 2 (HPO 3 ) 2 (H 2 PO 3 )(C 2 O 4 )](C 6 N 2 H 16 ) 0.5 (II) have been synthesized under solvothermal and hydrothermal conditions, respectively and further characterized by powder X-ray diffraction, IR spectroscopy, TGA, ICP-AES and elemental analyses. Single crystal X-ray diffraction reveals that the striking feature of I and II is that they possess the same second building unit (SBU) Ga 2 P 2 constructed from two GaO 6 octahedra and two [HPO 3 2− ] pseudo-pyramids sharing oxygen atoms. However, due to the different connecting fashions of SBUs, [C 2 O 4 2− ] groups and [H 2 PO 3 − ] pseudo-pyramids, the final frameworks of them are distinctly different. Compound I shows 2D layered structures with 8-membered ring (8-MR) windows in the ab plane while compound II presents a 3D open-framework with 8-MR channels along the b axis. - Graphical abstract: Using N, N-dimethyl-piperazine as structure directing agent, two new gallium phosphite-oxalates I showing 2D layered structure and II presenting 3D open-framework have been synthesized under solvothermal and hydrothermal conditions, respectively. - Highlights: • Using N, N-dimethyl-piperazine as structure directing agent, two new gallium phosphite-oxalates have been synthesized under solvothermal and hydrothermal conditions, respectively. • The same second building unit (SBU) is displayed in both compounds. • Compound I shows 2D layered structure with 8-MR windows while compound II presents 3D open-framework with 8-MR channels. • The solvent plays an important role on the formation of microporous compounds

Competitive and Cooperative Effects during Nickel Adsorption to Iron Oxides in the Presence of Oxalate

Energy Technology Data Exchange (ETDEWEB)

Flynn, Elaine D. [Department of Earth and Planetary; Catalano, Jeffrey G. [Department of Earth and Planetary

2017-08-09

Iron oxides are ubiquitous in soils and sediments and play a critical role in the geochemical distribution of trace elements and heavy metals via adsorption and coprecipitation. The presence of organic acids may potentially alter how metals associate with iron oxide minerals through a series of cooperative or competitive processes: solution complexation, ternary surface complexation, and surface site competition. The macroscopic and molecular-scale effects of these processes were investigated for Ni adsorption to hematite and goethite at pH 7 in the presence of oxalate. The addition of this organic acid suppresses Ni uptake on both minerals. Aqueous speciation suggests that this is dominantly the result of oxalate complexing and solubilizing Ni. Comparison of the Ni surface coverage to the concentration of free (uncomplexed) Ni²⁺ in solution suggests that the oxalate also alters Ni adsorption affinity. EXAFS and ATR-FTIR spectroscopies indicate that these changes in binding affinity are due to the formation of Ni–oxalate ternary surface complexes. These observations demonstrate that competition between dissolved oxalate and the mineral surface for Ni overwhelms the enhancement in adsorption associated with ternary complexation. Oxalate thus largely enhances Ni mobility, thereby increasing micronutrient bioavailability and inhibiting contaminant sequestration.

Biological Control of Meloidogyne incognita by Aspergillus niger F22 Producing Oxalic Acid.

Directory of Open Access Journals (Sweden)

Ja Yeong Jang

Full Text Available Restricted usage of chemical nematicides has led to development of environmentally safe alternatives. A culture filtrate of Aspergillus niger F22 was highly active against Meloidogyne incognita with marked mortality of second-stage juveniles (J2s and inhibition of egg hatching. The nematicidal component was identified as oxalic acid by organic acid analysis and gas chromatography-mass spectroscopy (GC-MS. Exposure to 2 mmol/L oxalic acid resulted in 100% juvenile mortality at 1 day after treatment and suppressed egg hatching by 95.6% at 7 days after treatment. Oxalic acid showed similar nematicidal activity against M. hapla, but was not highly toxic to Bursaphelenchus xylophilus. The fungus was incubated on solid medium and dried culture was used for preparation of a wettable powder-type (WP formulation as an active ingredient. Two WP formulations, F22-WP10 (ai 10% and oxalic acid-WP8 (ai 8%, were prepared using F22 solid culture and oxalic acid. In a field naturally infested with M. incognita, application of a mixture of F22-WP10 + oxalic acid-WP8 at 1,000- and 500-fold dilutions significantly reduced gall formation on the roots of watermelon plants by 58.8 and 70.7%, respectively, compared to the non-treated control. The disease control efficacy of the mixture of F22-WP10 + oxalic acid-WP8 was significantly higher than that of a chemical nematicide, Sunchungtan (ai 30% fosthiazate. These results suggest that A. niger F22 can be used as a microbial nematicide for the control of root-knot nematode disease.

Evidence of a natural marine source of oxalic acid and a possible link to glyoxal

Science.gov (United States)

Rinaldi, Matteo; Decesari, Stefano; Carbone, Claudio; Finessi, Emanuela; Fuzzi, Sandro; Ceburnis, Darius; O'Dowd, Colin D.; Sciare, Jean; Burrows, John P.; Vrekoussis, Mihalis; Ervens, Barbara; Tsigaridis, Kostas; Facchini, Maria Cristina

2011-08-01

This paper presents results supporting the existence of a natural source of oxalic acid over the oceans. Oxalate was detected in "clean-sector" marine aerosol samples at Mace Head (Ireland) (53°20'N, 9°54'W) during 2006, and at Amsterdam Island (37°48'S, 77°34'E) from 2003 to 2007, in concentrations ranging from 2.7 to 39 ng m-3 and from 0.31 to 17 ng m-3, respectively. The oxalate concentration showed a clear seasonal trend at both sites, with maxima in spring-summer and minima in fall-winter, being consistent with other marine biogenic aerosol components (e.g., methanesulfonic acid, non-sea-salt sulfate, and aliphatic amines). The observed oxalate was distributed along the whole aerosol size spectrum, with both a submicrometer and a supermicrometer mode, unlike the dominant submicrometer mode encountered in many polluted environments. Given its mass size distribution, the results suggest that over remote oceanic regions oxalate is produced through a combination of different formation processes. It is proposed that the cloud-mediated oxidation of gaseous glyoxal, recently detected over remote oceanic regions, may be an important source of submicrometer oxalate in the marine boundary layer. Supporting this hypothesis, satellite-retrieved glyoxal column concentrations over the two sampling sites exhibited the same seasonal concentration trend of oxalate. Furthermore, chemical box model simulations showed that the observed submicrometer oxalate concentrations were consistent with the in-cloud oxidation of typical marine air glyoxal mixing ratios, as retrieved by satellite measurements, at both sites.

Theoretical calculation of zero field splitting parameters of Cr{sup 3+} doped ammonium oxalate monohydrate

Energy Technology Data Exchange (ETDEWEB)

Kripal, Ram, E-mail: ram_kripal2001@rediffmail.com; Yadav, Awadhesh Kumar, E-mail: aky.physics@gmail.com

2015-06-15

Zero field splitting parameters (ZFSPs) D and E of Cr{sup 3+} ion doped ammonium oxalate monohydrate (AOM) are calculated with formula using the superposition model. The theoretically calculated ZFSPs for Cr{sup 3+} in AOM crystal are compared with the experimental value obtained by electron paramagnetic resonance (EPR). Theoretical ZFSPs are in good agreement with the experimental ones. The energy band positions of optical absorption spectra of Cr{sup 3+} in AOM crystal calculated with CFA package are in good match with the experimental values.

ROLE OF THE MICROFLORA IN DISTAL INTESTINAL TRACT BY MAINTAINING OXALATE HOMEOSTASIS

Directory of Open Access Journals (Sweden)

Osolodchenko T.P.

2015-05-01

Full Text Available Human intestinal microflora is part of the human body and performs numerous function. Considerable research interest is in the field of probiotics for the prevention of kidney stones, which is one of the most common urological diseases.Urolithiasis is one of the most common urological diseases. This is polyetiological disease congenital and acquired character with complex physical and chemical processes that occur not only in the urinary system, but also the whole body. None of the treatments does not guarantee full recovery of the patient and often leads to relapse. The open methods of removal stones yield news minimally invasive the technologys. Development of stone formation depends on the presence of many factors, metabolic disorders, chronic urinary tract infections, genetic disorders and more. Most have the following metabolic disorders as hypercalciuria, hiperurikuria, hipotsytraturia , hyperoxaluria and hipomahniuria. Among all types of urolithiasis kaltsiyoksalatnyy ranked first in the prevalence rate - about 75.0 - 85.0 % of cases. Dietary restriction by oxalates іs the unreliable method of preventing disease. Although there is evidence for the growth inhibition normobiocenosis representatives, which in turn enhances the absorption of salts of oxalic acid oxalate in the application of sodium , magnesium and cobalt in their intragastric administration. Recently published many papers on the impact on the level of oxalate intestinal microflora. The first publications appeared on the influence of gram-negative obligate anaerobes O. formigenes the concentration of oxalate in the urine. This anaerobic bacteria living in the colon, its prevalence - 46.0 % - 77.0 % of the adult population. O. formigenes reveals the symbiotic interaction with the human body by reducing absorption of oxalate in the intestinal cavity with subsequent decrease in their concentration in plasma and urine. O. formigenes has two key enzymes - oksalyl

Influence of the cone angle and crystal shape on the formation of twins in InP crystals

International Nuclear Information System (INIS)

Li, Xiaolan; Yang, Ruixia; Yang, Fan; Sun, Tongnian; Sun, Niefeng

2012-01-01

We present the investigation of twinning phenomena of LEC InP crystal growth which has been carried out in our laboratory in recent years. It is observed that the yield of twin-free single crystal InP can be grown by control the cone angle and crystal shape of a gradually increased diameter. Twin formation has been correlated to many growth factors. The influence of ingot shape on the formation of twins can be looked as the conical angle dependent twin probability of InP crystals. Twin-free InP crystals can be grown by large cone angle over 75 to 90 . (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Hyperoxaluria Requires TNF Receptors to Initiate Crystal Adhesion and Kidney Stone Disease.

Science.gov (United States)

Mulay, Shrikant R; Eberhard, Jonathan N; Desai, Jyaysi; Marschner, Julian A; Kumar, Santhosh V R; Weidenbusch, Marc; Grigorescu, Melissa; Lech, Maciej; Eltrich, Nuru; Müller, Lisa; Hans, Wolfgang; Hrabě de Angelis, Martin; Vielhauer, Volker; Hoppe, Bernd; Asplin, John; Burzlaff, Nicolai; Herrmann, Martin; Evan, Andrew; Anders, Hans-Joachim

2017-03-01

Intrarenal crystals trigger inflammation and renal cell necroptosis, processes that involve TNF receptor (TNFR) signaling. Here, we tested the hypothesis that TNFRs also have a direct role in tubular crystal deposition and progression of hyperoxaluria-related CKD. Immunohistochemical analysis revealed upregulated tubular expression of TNFR1 and TNFR2 in human and murine kidneys with calcium oxalate (CaOx) nephrocalcinosis-related CKD compared with controls. Western blot and mRNA expression analyses in mice yielded consistent data. When fed an oxalate-rich diet, wild-type mice developed progressive CKD, whereas Tnfr1-, Tnfr2- , and Tnfr1/2- deficient mice did not. Despite identical levels of hyperoxaluria, Tnfr1-, Tnfr2- , and Tnfr1/2 -deficient mice also lacked the intrarenal CaOx deposition and tubular damage observed in wild-type mice. Inhibition of TNFR signaling prevented the induced expression of the crystal adhesion molecules, CD44 and annexin II, in tubular epithelial cells in vitro and in vivo , and treatment with the small molecule TNFR inhibitor R-7050 partially protected hyperoxaluric mice from nephrocalcinosis and CKD. We conclude that TNFR signaling is essential for CaOx crystal adhesion to the luminal membrane of renal tubules as a fundamental initiating mechanism of oxalate nephropathy. Furthermore, therapeutic blockade of TNFR might delay progressive forms of nephrocalcinosis in oxalate nephropathy, such as primary hyperoxaluria. Copyright © 2017 by the American Society of Nephrology.

In vitro dissolution of calcium oxalate stones with ethylenediaminetetraacetic acid and snake venom thrombin-like enzyme.

Science.gov (United States)

Zhou, Xiang-Jun; Zhang, Jie; Zhang, Ci; Xu, Chang-Geng

2014-01-01

The aim of this study was to determine the feasibility of using snake venom thrombin-like enzyme (SVTLE) and/or ethylenediaminetetraacetic acid (EDTA) to dissolve calcium oxalate stones in vitro. Seven calcium oxalate stones were incubated with various chemolytic agents [EDTA, Tris-HCl/EDTA (TE) buffer or SVTLE diluted in TE buffer]. The pH, calcium concentration, stone weight and stone surface integrity were recorded, as well as related pathological changes to bladder mucosae. Compared to all other solutions, those containing SVTLE and buffered EDTA had higher concentrations of mobilized calcium and caused significantly more stone weight loss, stone fragility and gaps in the calcium crystals. Also, there were no adverse pathological effects on rabbit bladder mucosae from any of the solutions. The data indicate that buffered EDTA and SVTLE can be used to dissolve calcium oxalate stones and, at the concentrations used here, do not damage tissue. 2013 S. Karger AG, Basel.

Oxalic acid induced hydrothermal synthesis of single crystalline tungsten oxide nanorods

International Nuclear Information System (INIS)

Patil, V.B.; Adhyapak, P.V.; Suryavanshi, S.S.; Mulla, I.S.

2014-01-01

Highlights: • We report synthesis of 1D tungsten oxide using a hydrothermal route at 170 °C. • Oxalic acid plays an important role in the formation of 1D nanostructure. • Monoclinic transforms to hexagonal phase with increment in reaction duration. -- Abstract: One-dimensional single-crystalline tungsten oxide nanorods have been synthesized by the hydrothermal technique. The controlled morphology of tungsten oxide was obtained by using sodium tungstate and oxalic acid as an organic inducer. The reaction was carried out at 170 °C for 24, 48 and 72 h. The obtained tungsten oxides were investigated by using XRD, SEM and HRTEM techniques. In order to understand the role of organic inducer on the shape, size and phase formation of WO 3 was prepared with and without organic inducer. On heating of sodium tungstate without organic inducer for 72 h at 170 °C in the hydrothermal unit we obtain nanoparticles of monoclinic WO 3 , however, on addition of oxalic acid a single phase hexagonal WO 3 with distinct nanorods was formed. On addition of oxalic acid a systematic emergence of nanorod-like morphology was obtained with incrementing reaction times from 24 h to 48 h. The 72 h reaction generates self-assembled 20–30 nm diameter and 4–5 μm long h-WO 3 bundles of nanorods. The XRD studies show hexagonal structure of tungsten oxide, while SAED reveals its single crystalline nature. The photoluminescence (PL) emission spectrum shows a characteristic blue emission peak at 3 eV (410 nm). Raman spectra provide the evidence of hexagonal structure with stretching vibrations (830 cm −1 ) for 72 h of heating at 170 °C

Oxalic acid induced hydrothermal synthesis of single crystalline tungsten oxide nanorods

Energy Technology Data Exchange (ETDEWEB)

Patil, V.B. [School of Physical Sciences, Solapur University, Solapur 413255 (India); Adhyapak, P.V. [Centre for Materials for Electronic Technology (C-MET), Pune 411008 (India); Suryavanshi, S.S., E-mail: sssuryavanshi@rediffmail.com [School of Physical Sciences, Solapur University, Solapur 413255 (India); Mulla, I.S., E-mail: ismulla2001@gmail.com [Emeritus Scientist (CSIR), Centre for Materials for Electronic Technology (C-MET), Pune 411008 (India)

2014-03-25

Highlights: • We report synthesis of 1D tungsten oxide using a hydrothermal route at 170 °C. • Oxalic acid plays an important role in the formation of 1D nanostructure. • Monoclinic transforms to hexagonal phase with increment in reaction duration. -- Abstract: One-dimensional single-crystalline tungsten oxide nanorods have been synthesized by the hydrothermal technique. The controlled morphology of tungsten oxide was obtained by using sodium tungstate and oxalic acid as an organic inducer. The reaction was carried out at 170 °C for 24, 48 and 72 h. The obtained tungsten oxides were investigated by using XRD, SEM and HRTEM techniques. In order to understand the role of organic inducer on the shape, size and phase formation of WO{sub 3} was prepared with and without organic inducer. On heating of sodium tungstate without organic inducer for 72 h at 170 °C in the hydrothermal unit we obtain nanoparticles of monoclinic WO{sub 3}, however, on addition of oxalic acid a single phase hexagonal WO{sub 3} with distinct nanorods was formed. On addition of oxalic acid a systematic emergence of nanorod-like morphology was obtained with incrementing reaction times from 24 h to 48 h. The 72 h reaction generates self-assembled 20–30 nm diameter and 4–5 μm long h-WO{sub 3} bundles of nanorods. The XRD studies show hexagonal structure of tungsten oxide, while SAED reveals its single crystalline nature. The photoluminescence (PL) emission spectrum shows a characteristic blue emission peak at 3 eV (410 nm). Raman spectra provide the evidence of hexagonal structure with stretching vibrations (830 cm{sup −1}) for 72 h of heating at 170 °C.

Investigation of organic desulfurization additives affecting the calcium sulfate crystals formation

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Lv Lina

2017-01-01

Full Text Available In the study, the optimal experimental conditions for gypsum crystals formation were 323 K, 300 rpm stirring speed. The major impurities of Mg2+, Al3+ and Fe3+ were found to inhibit calcium sulfate crystals formation. Fe3+ caused the strongest inhibition, followed by Mg2+ and Al3+. The influence of desulfurization additives on the gypsum crystals formation was explored with the properties of moisture content, particle size distribution and crystal morphology. The organic desulfurization additives of adipic acid, citric acid, sodium citrate and benzoic acid were investigated. Citric acid and sodium citrate were found to improve the quality of gypsum. Moisture contents were reduced by more than 50%, gypsum particle sizes were respectively enlarged by 9.1 and 22.8%, induction time extended from 4.3 (blank to 5.3 and 7.8 min, and crystal morphology trended to be thicker.

Crystal-free Formation of Non-Oxide Optical Fiber

Science.gov (United States)

Nabors, Sammy A.

2015-01-01

Researchers at NASA Marshall Space Flight Center have devised a method for the creation of crystal-free nonoxide optical fiber preforms. Non-oxide fiber optics are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. However, some of these glasses are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. NASA has developed a new method of non-oxide fiber formation that uses axial magnetic fields to suppress crystallization. The resulting non-oxide fibers are crystal free and have lower signal attenuation rates than silica based optical fibers.

Precipitation of plutonium oxalate from homogeneous solutions

International Nuclear Information System (INIS)

Rao, V.K.; Pius, I.C.; Subbarao, M.; Chinnusamy, A.; Natarajan, P.R.

1986-01-01

A method for the precipitation of plutonium(IV) oxalate from homogeneous solutions using diethyl oxalate is reported. The precipitate obtained is crystalline and easily filterable with yields in the range of 92-98% for precipitations involving a few mg to g quantities of plutonium. Decontamination factors for common impurities such as U(VI), Am(III) and Fe(III) were determined. TGA and chemical analysis of the compound indicate its composition as Pu(Csub(2)Osub(4))sub(2).6Hsub(2)O. Data are obtained on the solubility of the oxalate in nitric acid and in mixtures of nitric acid and oxalic acid of varying concentrations. Green PuOsub(2) obtained by calcination of the oxalate has specifications within the recommended values for trace foreign substances such as chlorine, fluorine, carbon and nitrogen. (author)

The production of (14C) oxalate during the metabolism of (14C) carbohydrates in isolated rat hepatocytes.

Science.gov (United States)

Rofe, A M; James, H M; Bais, R; Edwards, J B; Conyers, R A

1980-04-01

carbohydrates, particularly fructose, contribute to endogenous oxalate production lends support to the hypothesis that a high sucrose consumption contributes to the formation of renal oxalate stones in man.

Advanced Oxidation: Oxalate Decomposition Testing With Ozone

International Nuclear Information System (INIS)

Ketusky, E.; Subramanian, K.

2012-01-01

At the Savannah River Site (SRS), oxalic acid is currently considered the preferred agent for chemically cleaning the large underground Liquid Radioactive Waste Tanks. It is applied only in the final stages of emptying a tank when generally less than 5,000 kg of waste solids remain, and slurrying based removal methods are no-longer effective. The use of oxalic acid is preferred because of its combined dissolution and chelating properties, as well as the fact that corrosion to the carbon steel tank walls can be controlled. Although oxalic acid is the preferred agent, there are significant potential downstream impacts. Impacts include: (1) Degraded evaporator operation; (2) Resultant oxalate precipitates taking away critically needed operating volume; and (3) Eventual creation of significant volumes of additional feed to salt processing. As an alternative to dealing with the downstream impacts, oxalate decomposition using variations of ozone based Advanced Oxidation Process (AOP) were investigated. In general AOPs use ozone or peroxide and a catalyst to create hydroxyl radicals. Hydroxyl radicals have among the highest oxidation potentials, and are commonly used to decompose organics. Although oxalate is considered among the most difficult organic to decompose, the ability of hydroxyl radicals to decompose oxalate is considered to be well demonstrated. In addition, as AOPs are considered to be 'green' their use enables any net chemical additions to the waste to be minimized. In order to test the ability to decompose the oxalate and determine the decomposition rates, a test rig was designed, where 10 vol% ozone would be educted into a spent oxalic acid decomposition loop, with the loop maintained at 70 C and recirculated at 40L/min. Each of the spent oxalic acid streams would be created from three oxalic acid strikes of an F-area simulant (i.e., Purex = high Fe/Al concentration) and H-area simulant (i.e., H area modified Purex = high Al/Fe concentration) after nearing

ADVANCED OXIDATION: OXALATE DECOMPOSITION TESTING WITH OZONE

Energy Technology Data Exchange (ETDEWEB)

Ketusky, E.; Subramanian, K.

2012-02-29

At the Savannah River Site (SRS), oxalic acid is currently considered the preferred agent for chemically cleaning the large underground Liquid Radioactive Waste Tanks. It is applied only in the final stages of emptying a tank when generally less than 5,000 kg of waste solids remain, and slurrying based removal methods are no-longer effective. The use of oxalic acid is preferred because of its combined dissolution and chelating properties, as well as the fact that corrosion to the carbon steel tank walls can be controlled. Although oxalic acid is the preferred agent, there are significant potential downstream impacts. Impacts include: (1) Degraded evaporator operation; (2) Resultant oxalate precipitates taking away critically needed operating volume; and (3) Eventual creation of significant volumes of additional feed to salt processing. As an alternative to dealing with the downstream impacts, oxalate decomposition using variations of ozone based Advanced Oxidation Process (AOP) were investigated. In general AOPs use ozone or peroxide and a catalyst to create hydroxyl radicals. Hydroxyl radicals have among the highest oxidation potentials, and are commonly used to decompose organics. Although oxalate is considered among the most difficult organic to decompose, the ability of hydroxyl radicals to decompose oxalate is considered to be well demonstrated. In addition, as AOPs are considered to be 'green' their use enables any net chemical additions to the waste to be minimized. In order to test the ability to decompose the oxalate and determine the decomposition rates, a test rig was designed, where 10 vol% ozone would be educted into a spent oxalic acid decomposition loop, with the loop maintained at 70 C and recirculated at 40L/min. Each of the spent oxalic acid streams would be created from three oxalic acid strikes of an F-area simulant (i.e., Purex = high Fe/Al concentration) and H-area simulant (i.e., H area modified Purex = high Al/Fe concentration

2,4-Diamino-6-methyl-1,3,5-triazin-1-ium hydrogen oxalate

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Bohari M. Yamin

2012-05-01

Full Text Available The title compound, C4H8N5+·C2HO4−, was obtained from the reaction of oxalic acid and 2,4-diamino-6-methyl-1,3,5-triazine. The protonated triazine ring is essentially planar with a maximum deviation of 0.035 (1 Å, but the hydrogen oxalate anion is less planar, with a maximum deviation of 0.131 (1 Å for both carbonyl O atoms. In the crystal, the ions are linked by intermolecular N—H...O, N—H...N, O—H...O and C—H...O hydrogen bonds, forming a three-dimensional network. Weak π–π [centroid–centroid distance = 3.763 Å] and C—O...π interactions [O...centroid = 3.5300 (16 Å, C—O...centroid = 132.19 (10°] are also present.

Development and characterization of oxalate coatings for the corrosion protection of metallic zinc

International Nuclear Information System (INIS)

Oliveira, M.; Ferreira Junior, J.M.; Baker, M.A.; Rossi, J.; Costa, I.

2016-01-01

This work aims to develop and characterize surface treatments for corrosion protection of zinc. Oxalic acid (OA) was used and the concentration range selected was from 10"-"1 M to 1 M. The chemical composition of the layers formed was evaluated by XPS, and the morphology and thickness, by FIB and EDS, respectively. The corrosion resistance was monitored by Electrochemical Impedance Spectroscopy (EIS). The results showed that a zinc oxalate layer had been formed in both concentrations but of different thickness and crystal sizes but similar morphology. The EIS results showed that the layer formed in the lower concentration solution provided corrosion protection for long periods whereas the one obtained at higher concentration did not protect the surface. The results led to conclude that one of the treatments tested is highly indicated for corrosion protection of zinc. (author)

Redox Cycling, pH Dependence, and Ligand Effects of Mn(III) in Oxalate Decarboxylase from Bacillus subtilis.

Science.gov (United States)

Twahir, Umar T; Ozarowski, Andrew; Angerhofer, Alexander

2016-11-29

This contribution describes electron paramagnetic resonance (EPR) experiments on Mn(III) in oxalate decarboxylase of Bacillus subtilis, an interesting enzyme that catalyzes the redox-neutral dissociation of oxalate into formate and carbon dioxide. Chemical redox cycling provides strong evidence that both Mn centers can be oxidized, although the N-terminal Mn(II) appears to have the lower reduction potential and is most likely the carrier of the +3 oxidation state under moderate oxidative conditions, in agreement with the general view that it represents the active site. Significantly, Mn(III) was observed in untreated OxDC in succinate and acetate buffers, while it could not be directly observed in citrate buffer. Quantitative analysis showed that up to 16% of the EPR-visible Mn is in the +3 oxidation state at low pH in the presence of succinate buffer. The fine structure and hyperfine structure parameters of Mn(III) are affected by small carboxylate ligands that can enter the active site and have been recorded for formate, acetate, and succinate. The results from a previous report [Zhu, W., et al. (2016) Biochemistry 55, 429-434] could therefore be reinterpreted as evidence of formate-bound Mn(III) after the enzyme is allowed to turn over oxalate. The pH dependence of the Mn(III) EPR signal compares very well with that of enzymatic activity, providing strong evidence that the catalytic reaction of oxalate decarboxylase is driven by Mn(III), which is generated in the presence of dioxygen.

The promotion effect of coexisting hygroscopic composition on the reaction between oxalic acid and calcite during humidifying process

Science.gov (United States)

Ma, Q.; He, H.

2012-12-01

Internally mixed oxalic acid with mineral dust has been frequently detected in field measurements (Sullivan and Prather, 2007; Wang et al., 2012; Yang et al., 2009). Meanwhile, Furukawa and Takahashi (Furukawa and Takahashi, 2011) found that most of the oxalic acid in mineral mixture is present as metal oxalate complexes in the aerosols, however, the formation mechanism of these complexes is not well known. It was reported that cloud process of H2C2O4/CaCO3 mixture could lead to the formation of calcium oxalate (Gierlus et al., 2012). Recently, we used Raman spectroscopy to investigate the hygroscopic behavior of H2C2O4/CaCO3 mixture below saturation condition as well as the effect of coexisting hygroscopic compositions, e.g. Ca(NO3)2, NaCl, NH4NO3, and (NH4)2SO4. It was found that there was no interaction between H2C2O4 and calcite without third component during humidifying process under ambient condition. In contrast, the presence of coexisting Ca(NO)3, NaCl, or NH4NO3 could promote the reaction between H2C2O4 and calcite by providing an aqueous circumstance after deliquescence, resulting in the formation of calcium oxalate hydrates. Moreover, substitution of strong acid (HNO3) by medium acid (H2C2O4) occurred when water vapor was absorbed in Ca(NO3)2/H2C2O4 mixture (Ma and He, 2012). As for (NH4)2SO4, there existed a competition effect between (NH4)2SO4 and H2C2O4 for the reaction with CaCO3. CaCO3 was preferentially reacted with (NH4)2SO4 to form gypsum in the solution, while the residual NH4+ and C2O42- ions were bonded to (NH4)2C2O4 after efflorescence. These results implies a potential formation pathway of metal oxalate complexes in the atmosphere and also suggests that synergistic effect between different constituents in humidifying process of mixed particles should be considered in future hygroscopic behavior studies.

Kinetics and mechanism of the oxidation of formic and oxalic acids ...

Indian Academy of Sciences (India)

The oxidation of formic and oxalic acids by benzyltrimethylammonium dichloroiodate (BTMACI), in the presence of zinc chloride, leads to the formation of carbon dioxide. The reaction is first order with respect to BTMACI, zinc chloride and organic acid. Oxidation of deuteriated formic acid indicates the presence of a kinetic ...

Entropy-driven crystal formation on highly strained substrates

KAUST Repository

Savage, John R.

2013-05-20

In heteroepitaxy, lattice mismatch between the deposited material and the underlying surface strongly affects nucleation and growth processes. The effect of mismatch is well studied in atoms with growth kinetics typically dominated by bond formation with interaction lengths on the order of one lattice spacing. In contrast, less is understood about how mismatch affects crystallization of larger particles, such as globular proteins and nanoparticles, where interparticle interaction energies are often comparable to thermal fluctuations and are short ranged, extending only a fraction of the particle size. Here, using colloidal experiments and simulations, we find particles with short-range attractive interactions form crystals on isotropically strained lattices with spacings significantly larger than the interaction length scale. By measuring the free-energy cost of dimer formation on monolayers of increasing uniaxial strain, we show the underlying mismatched substrate mediates an entropy-driven attractive interaction extending well beyond the interaction length scale. Remarkably, because this interaction arises from thermal fluctuations, lowering temperature causes such substrate-mediated attractive crystals to dissolve. Such counterintuitive results underscore the crucial role of entropy in heteroepitaxy in this technologically important regime. Ultimately, this entropic component of lattice mismatched crystal growth could be used to develop unique methods for heterogeneous nucleation and growth of single crystals for applications ranging from protein crystallization to controlling the assembly of nanoparticles into ordered, functional superstructures. In particular, the construction of substrates with spatially modulated strain profiles would exploit this effect to direct self-assembly, whereby nucleation sites and resulting crystal morphology can be controlled directly through modifications of the substrate.

Studies in the solubility of Pu(III) oxalate

Energy Technology Data Exchange (ETDEWEB)

Hasilkar, S P; Khedekar, N B; Chander, K; Jadhav, V; Jain, H C [Bhabha Atomic Research Centre, Bombay (India). Fuel Reprocessing Div.

1994-11-01

Studies have been carried out on the solubility of Pu(III) oxalate by precipitation of Pu(III) oxalate from varying concentrations of HNO[sub 3]/HCl (0.5-2.0M) solutions and also by equilibrating freshly prepared Pu(III) oxalate with solutions containing varying concentrations of HNO[sub 3]/HCl, oxalic acid and ascorbic acid. Pu(III) solutions in HNO[sub 3] and HCl media were prepared by reduction of Pu(IV) with ascorbic acid. 0.01-0.10M ascorbic acid concentration in the aqueous solution was maintained as holding reductant. The solubility of Pu(III) oxalate was found to be a minimum in 0.5M-1M HNO[sub 3]/HCl solutions containing 0.05M ascorbic acid and 0.2M excess oxalic acid in the supernatant. (author) 6 refs.; 6 tabs.

Comprehensive physicochemical studies of a new hybrid material: 2-Amino-4-methyl-3-nitropyridinium hydrogen oxalate

Science.gov (United States)

Bryndal, I.; Kucharska, E.; Wandas, M.; Lorenc, J.; Hermanowicz, K.; Mączka, M.; Lis, T.; Marchewka, M.; Hanuza, J.

2014-01-01

A new organic-organic salt, 2-amino-4-methyl-3-nitropyridinium hydrogen oxalate (AMNPO), and its deuterium analogue have been synthesized and characterized by means of FT-IR, FT-Raman, DSC and single crystal X-ray studies. The DSC measurements and temperature dependence of the IR and Raman spectra in the range 4-295 K show that it undergoes a reversible phase transition at ∼240 K. At room temperature it crystallizes in noncentrosymmetric space group P21. The unit-cell is built of the 2-amino-4-methyl-3-nitropyridinium cations and oxalate monoanions which are connected via the Nsbnd H⋯O and Osbnd H⋯O hydrogen bonds. The geometrical and hydrogen bond parameters are similar for non-deuterated (at 120 and 293 K) and deuterated compounds (at 90 K). The phase transition is probably a consequence of order-disorder transition inside of hydrogen network. The 6-311G(2d,2p) basis set with B3LYP functional have been used to discuss the structure and vibrational spectra of the studied compound.

Pseudomonas fluorescens ATCC 13525 Containing an Artificial Oxalate Operon and Vitreoscilla Hemoglobin Secretes Oxalic Acid and Solubilizes Rock Phosphate in Acidic Alfisols

Science.gov (United States)

Archana, G.; Naresh Kumar, G.

2014-01-01

Oxalate secretion was achieved in Pseudomonas fluorescens ATCC 13525 by incorporation of genes encoding Aspergillus niger oxaloacetate acetyl hydrolase (oah), Fomitopsis plaustris oxalate transporter (FpOAR) and Vitreoscilla hemoglobin (vgb) in various combinations. Pf (pKCN2) transformant containing oah alone accumulated 19 mM oxalic acid intracellularly but secreted 1.2 mM. However, in the presence of an artificial oxalate operon containing oah and FpOAR genes in plasmid pKCN4, Pf (pKCN4) secreted 13.6 mM oxalate in the medium while 3.6 mM remained inside. This transformant solubilized 509 μM of phosphorus from rock phosphate in alfisol which is 4.5 fold higher than the Pf (pKCN2) transformant. Genomic integrants of P. fluorescens (Pf int1 and Pf int2) containing artificial oxalate operon (plac-FpOAR-oah) and artificial oxalate gene cluster (plac-FpOAR-oah, vgb, egfp) secreted 4.8 mM and 5.4 mM oxalic acid, released 329 μM and 351 μM P, respectively, in alfisol. The integrants showed enhanced root colonization, improved growth and increased P content of Vigna radiata plants. This study demonstrates oxalic acid secretion in P. fluorescens by incorporation of an artificial operon constituted of genes for oxalate synthesis and transport, which imparts mineral phosphate solubilizing ability to the organism leading to enhanced growth and P content of V. radiata in alfisol soil. PMID:24705024

Pseudomonas fluorescens ATCC 13525 containing an artificial oxalate operon and Vitreoscilla hemoglobin secretes oxalic acid and solubilizes rock phosphate in acidic alfisols.

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Kavita Yadav

Full Text Available Oxalate secretion was achieved in Pseudomonas fluorescens ATCC 13525 by incorporation of genes encoding Aspergillus niger oxaloacetate acetyl hydrolase (oah, Fomitopsis plaustris oxalate transporter (FpOAR and Vitreoscilla hemoglobin (vgb in various combinations. Pf (pKCN2 transformant containing oah alone accumulated 19 mM oxalic acid intracellularly but secreted 1.2 mM. However, in the presence of an artificial oxalate operon containing oah and FpOAR genes in plasmid pKCN4, Pf (pKCN4 secreted 13.6 mM oxalate in the medium while 3.6 mM remained inside. This transformant solubilized 509 μM of phosphorus from rock phosphate in alfisol which is 4.5 fold higher than the Pf (pKCN2 transformant. Genomic integrants of P. fluorescens (Pf int1 and Pf int2 containing artificial oxalate operon (plac-FpOAR-oah and artificial oxalate gene cluster (plac-FpOAR-oah, vgb, egfp secreted 4.8 mM and 5.4 mM oxalic acid, released 329 μM and 351 μM P, respectively, in alfisol. The integrants showed enhanced root colonization, improved growth and increased P content of Vigna radiata plants. This study demonstrates oxalic acid secretion in P. fluorescens by incorporation of an artificial operon constituted of genes for oxalate synthesis and transport, which imparts mineral phosphate solubilizing ability to the organism leading to enhanced growth and P content of V. radiata in alfisol soil.

Effect of coccolith polysaccharides isolated from the coccolithophorid, Emiliania huxleyi, on calcite crystal formation in in vitro CaCO3 crystallization.

Science.gov (United States)

Kayano, Keisuke; Saruwatari, Kazuko; Kogure, Toshihiro; Shiraiwa, Yoshihiro

2011-02-01

Marine coccolithophorids (Haptophyceae) produce calcified scales "coccoliths" which are composed of CaCO(3) and coccolith polysaccharides (CP) in the coccolith vesicles. CP was previously reported to be composed of uronic acids and sulfated residues, etc. attached to the polymannose main chain. Although anionic polymers are generally known to play key roles in biomineralization process, there is no experimental data how CP contributes to calcite crystal formation in the coccolithophorids. CP used was isolated from the most abundant coccolithophorid, Emiliania huxleyi. CaCO(3) crystallization experiment was performed on agar template layered onto a plastic plate that was dipped in the CaCO(3) crystallization solution. The typical rhombohedral calcite crystals were formed in the absence of CP. CaCO(3) crystals formed on the naked plastic plate were obviously changed to stick-like shapes when CP was present in the solution. EBSD analysis proved that the crystal is calcite of which c-axis was elongated. CP in the solution stimulated the formation of tabular crystals with flat edge in the agarose gel. SEM and FIB-TEM observations showed that the calcite crystals were formed in the gel. The formation of crystals without flat edge was stimulated when CP was preliminarily added in the gel. These observations suggest that CP has two functions: namely, one is to elongate the calcite crystal along c-axis and another is to induce tabular calcite crystal formation in the agarose gel. Thus, CP may function for the formation of highly elaborate species-specific structures of coccoliths in coccolithophorids.

Oxalic acid decreases calcium absorption in rats

International Nuclear Information System (INIS)

Weaver, C.M.; Martin, B.R.; Ebner, J.S.; Krueger, C.A.

1987-01-01

Calcium absorption from salts and foods intrinsically labeled with 45 Ca was determined in the rat model. Calcium bioavailability was nearly 10 times greater for low oxalate kale, CaCO 3 and CaCl 2 than from CaC 2 O 4 (calcium oxalate) and spinach (high in oxalates). Extrinsic and intrinsic labeling techniques gave a similar assessment of calcium bioavailability from kale but not from spinach

Sources and atmospheric processes impacting oxalate at a suburban coastal site in Hong Kong: Insights inferred from 1 year hourly measurements

Science.gov (United States)

Zhou, Yang; Huang, Xiaohui Hilda; Bian, Qijing; Griffith, Stephen M.; Louie, Peter K. K.; Yu, Jian Zhen

2015-09-01

Oxalic acid is one of the most abundant dicarboxylic acids in the atmosphere, receiving a great deal of attention due to its potential influence on cloud condensation nucleus activities. In this work, we report 10 months of hourly oxalate measurements in particulate matter of less than 2.5 µm in aerodynamic diameter (PM2.5) by a Monitor for Aerosols and Gases in ambient Air at a suburban coastal site in Hong Kong from April 2012 to February 2013. A total of more than 6000 sets of oxalate and inorganic ion data were obtained. The mean (±SD) oxalate concentration was 0.34 (±0.18) µg m-3, accounting for 2.8% of the total ion mass and 1.5% of the PM2.5 mass. Seasonal variation showed higher concentrations in fall and winter (0.54 and 0.36 µg m-3, respectively) and lower concentrations in spring and summer (~0.26 µg m-3). Different from the inorganic ions, a shallow dip in the oxalate concentration consistently occurred in the morning after sunrise (around 9:00 A.M.) throughout all seasons. Our analysis suggests that this was likely due to photolysis of oxalate-Fe (III) complex under sunlight. In summer, a small daytime peak was discernable for oxalate and nitrate. This characteristic, together with a more evident diurnal variation of O3, indicates comparatively more active photochemical oxidation in summer than other seasons. High correlations were observed between oxalate and non-sea-salt SO42- (NSS) (R2 = 0.63) and Ox (O3 + NO2) (R2 = 0.48), indicating significant commonality in their secondary formation. Positive matrix factorization analysis of oxalate and other real-time gas and particle-phase component data estimates that secondary formation processes, including secondary gas or aqueous oxidation processes (49%), oxidation processes of biomass burning emissions (37%), accounted for the majority of PM2.5 oxalate. A backward trajectories cluster analysis found that higher oxalate/NSS ratios were associated with low pollution samples under the influence of

Oxalate Content of Taro Leaves Grown in Central Vietnam

Science.gov (United States)

Du Thanh, Hang; Phan Vu, Hai; Vu Van, Hai; Le Duc, Ngoan; Le Minh, Tuan; Savage, Geoffrey

2017-01-01

Leaves were harvested from four different cultivars of Colocasia esculenta and three cultivars of Alocasia odora that were growing on nine different farms in central Vietnam. The total, soluble and insoluble oxalate contents of the leaves were extracted and measured using HPLC chromatography. Total calcium determinations were also carried out on the same samples. The total oxalate content of the leaves ranged from 433.8 to 856.1 mg/100 g wet matter (WM) while the soluble oxalate ranged from 147.8 to 339.7 mg/100 g WM. The proportion of soluble oxalate ranged from 28% to 41% (overall mean 35%) of the total oxalate content of the leaves. The equivalent insoluble oxalate proportion ranged from 59% to 72% of the total (overall mean 65%). There was little difference between the Colocasia esculenta and Alocasia odora taro cultivars, although the total oxalate content was significantly higher in Alocasia odora cultivars. The overall mean total calcium content was 279.5 mg/100 WM and the percentage of insoluble calcium bound as calcium oxalate ranged from 31.7% to 57.3% of the total calcium content (overall mean 47.1%). The oxalate content in taro leaves is a major factor to consider when different cultivars of taro are recommended for human or animal consumption. PMID:28231080

Oxalate quantification in hemodialysate to assess dialysis adequacy for primary hyperoxaluria.

Science.gov (United States)

Tang, Xiaojing; Voskoboev, Nikolay V; Wannarka, Stacie L; Olson, Julie B; Milliner, Dawn S; Lieske, John C

2014-01-01

Patients with primary hyperoxaluria (PH) overproduce oxalate which is eliminated via the kidneys. If end-stage kidney disease develops they are at high risk for systemic oxalosis, unless adequate oxalate is removed during hemodialysis (HD) to equal or exceed ongoing oxalate production. The purpose of this study was to validate a method to measure oxalate removal in this unique group of dialysis patients. Fourteen stable patients with a confirmed diagnosis of PH on HD were included in the study. Oxalate was measured serially in hemodialysate and plasma samples in order to calculate rates of oxalate removal. HD regimens were adjusted according to a given patient's historical oxalate production, amount of oxalate removal at dialysis, residual renal clearance of oxalate, and plasma oxalate levels. After a typical session of HD, plasma oxalate was reduced by 78.4 ± 7.7%. Eight patients performed HD 6 times/week, 2 patients 5 times/week, and 3 patients 3 times/week. Combined oxalate removal by HD and the kidneys was sufficient to match or exceed endogenous oxalate production. After a median period of 9 months, pre-dialysis plasma oxalate was significantly lower than initially (75.1 ± 33.4 vs. 54.8 ± 46.6 mmol/l, p = 0.02). This methodology can be used to individualize the dialysis prescription of PH patients to prevent oxalosis during the time they are maintained on HD and to reduce risk of oxalate injury to a transplanted kidney.

Oxalate Content of the Herb Good-King-Henry, Blitum Bonus-Henricus

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Wanying Li

2015-05-01

Full Text Available The total, soluble and insoluble oxalate contents of the leaves, stems and buds of Good-King-Henry (Blitum Bonus-Henricus were extracted and measured using HPLC chromatography. The large, mature leaves contained 42% more total oxalate than in the small leaves and the soluble oxalate content of the large leaves was 33% higher than the smaller leaves. Cooking the mixed leaves, stems and buds in boiling water for two minutes significantly (p < 0.05 reduced the total oxalate when compared to the raw plant parts. Pesto sauce made from mixed leaves contained 257 mg total oxalate/100 g fresh weight; this was largely made up of insoluble oxalates (85% of the total oxalate content. Soup made from mixed leaves contained lower levels of total oxalates (44.26 ± 0.49 mg total oxalate/100 g fresh weight and insoluble oxalate made up 49% of the oxalate contents. The levels of oxalates in the Good-King-Henry leaves were high, suggesting that the leaves should be consumed occasionally as a delicacy because of their unique taste rather than as a significant part of the diet. However, the products made from Good-King-Henry leaves indicated that larger amounts could be consumed as the oxalate levels were reduced by dilution and processing.

Crystals in brain and meninges in primary hyperoxaluria and oxalosis.

Science.gov (United States)

Haqqani, M T

1977-01-01

A case of primary hyperoxaluria and oxalosis with chronic renal failure, crystalline myocarditis, and disseminated calcium oxalate crystal deposition in various tissues including the brain and meninges is described. Deposition of crystals in brain and meninges is exceptionally rare in primary oxalosis. Images PMID:838867

Oxalate Content of Taro Leaves Grown in Central Vietnam

Directory of Open Access Journals (Sweden)

Hang Du Thanh

2017-01-01

Full Text Available Leaves were harvested from four different cultivars of Colocasia esculenta and three cultivars of Alocasia odora that were growing on nine different farms in central Vietnam. The total, soluble and insoluble oxalate contents of the leaves were extracted and measured using HPLC chromatography. Total calcium determinations were also carried out on the same samples. The total oxalate content of the leaves ranged from 433.8 to 856.1 mg/100 g wet matter (WM while the soluble oxalate ranged from 147.8 to 339.7 mg/100 g WM. The proportion of soluble oxalate ranged from 28% to 41% (overall mean 35% of the total oxalate content of the leaves. The equivalent insoluble oxalate proportion ranged from 59% to 72% of the total (overall mean 65%. There was little difference between the Colocasia esculenta and Alocasia odora taro cultivars, although the total oxalate content was significantly higher in Alocasia odora cultivars. The overall mean total calcium content was 279.5 mg/100 WM and the percentage of insoluble calcium bound as calcium oxalate ranged from 31.7% to 57.3% of the total calcium content (overall mean 47.1%. The oxalate content in taro leaves is a major factor to consider when different cultivars of taro are recommended for human or animal consumption.

Urinary oxalate to creatinine ratios in healthy Turkish schoolchildren.

Science.gov (United States)

Dursun, Ismail; Çelik, İlknur; Poyrazoglu, Hakan M; Köse, Kader; Tanrıkulu, Esen; Sahin, Habibe; Yılmaz, Kenan; Öztürk, Ahmet; Yel, Sibel; Gündüz, Zübeyde; Düşünsel, Ruhan

2017-11-01

we aimed to establish reference values for urinary oxalate to creatinine ratios in healthy children aged 6-15 years and to investigate the relationship between their nutritional habits and oxalate excretion. Random urine specimens from 953 healthy children aged 6-15 years were obtained and analyzed for oxalate and creatinine. Additionally, a 24-h dietary recall form was prepared and given to them. The ingredient composition of the diet was calculated. The children were divided into three groups according to age: Group I (69 years, n = 353), Group II (10-12 years, n = 335), and Group III (13-15 years, n = 265). The 95th percentile of the oxalate to creatinine ratio for subjects aged 6-9, 10-12, and 13-15 years were 0.048, 0.042, and 0.042 mg/mg, respectively. The oxalate to creatinine ratio was significantly higher in Group 1 than in Group 2 and Group 3. Urinary oxalate excretion was positively correlated with increased protein intake and negatively correlated with age. A significant positive correlation was determined between urinary oxalate excretion and the proline, serine, protein, and glycine content of diet. Dietary proline intake showed a positive correlation with the urine oxalate to creatinine ratio and was found to be an independent predictor for urinary oxalate. These data lend support to the idea that every country should have its own normal reference values to determine the underlying metabolic risk factor for kidney stone disease since regional variation in the dietary intake of proteins and other nutrients can affect normal urinary excretion of oxalate.

Relationship between mechanical properties and crystal structure in cocrystals and salt of paracetamol.

Science.gov (United States)

Ahmed, Hamzah; Shimpi, Manishkumar R; Velaga, Sitaram P

2017-01-01

Objectives were to study mechanical properties of various solid forms of paracetamol and relate to their crystal structures. Paracetamol form I (PRA), its cocrystals with oxalic acid (PRA-OXA) and 4,4-bipyridine (PRA-BPY) and hydrochloride salt (PRA-HCL) were selected. Cocrystals and salt were scaled-up using rational crystallization methods. The resulting materials were subjected to different solid-state characterizations. The powders were sieved and 90-360 µm sieve fraction was considered. These powders were examined by scanning electron microscopy (SEM) and densities were determined. Tablets were made at applied pressures of 35-180 MPa under controlled conditions and the tablet height, diameter and hardness were measured. Tensile strength and porosity of the tablets were estimated using well known models. Crystal structures of these systems were visualized and slip planes were identified. Cocrystal and salt of PRA were physically pure. Sieved powders had comparable morphologies and particle size. The apparent and theoretical densities of powders were similar, but no clear trends were observed. The tensile strengths of these compacts were increased with increasing pressure whereas tabletability decreased in the order oxalic acid > PRA-HCL ≈ PRA-OXA > BPY > PRA-BPY. Tablet tensile strength decreases exponentially with increasing porosity with the exception of PRY-BPY and BPY. Slip plane prediction based on attachment energies may not be independently considered. However, it was possible to explain the improved mechanical properties of powders based on the crystal structure. Cocrystallization and salt formation have introduced structural features that are responsible for improved tableting properties of PRA.

Composition, structure and electrical properties of alumina barrier layers grown in fluoride-containing oxalic acid solutions

Energy Technology Data Exchange (ETDEWEB)

Jagminas, A. [Institute of Chemistry, A. Gostauto 9, LT-01108 Vilnius (Lithuania)], E-mail: jagmin@ktl.mii.lt; Vrublevsky, I. [Department of Microelectricals, Belarusian State University of Informatics and Radioelectricals, 6 Brovka Street, Minsk 220013 (Belarus); Kuzmarskyte, J.; Jasulaitiene, V. [Institute of Chemistry, A. Gostauto 9, LT-01108 Vilnius (Lithuania)

2008-04-15

The composition, structure and electrical properties of alumina barrier layers grown by anodic oxidation in F{sup -}-containing (FC) and F{sup -}-free (FF) oxalic acid solutions were studied using the re-anodizing/dissolution technique, Fourier-transformed infrared and X-ray photoelectron spectroscopy. These results confirmed formation in FC anodizing solutions of films structurally different from ones grown in FF oxalic acid baths. It was found that the barrier layer of FC alumina films is composed of two layers differing in the dissolution rate. These differences are related to the formation in the FC electrolyte of a barrier layer composed of a more microporous outer part and a thin, non-porous and non-scalloped inner part consisting of aluminum oxide and aluminum fluoride.

Pseudomonas fluorescens ATCC 13525 Containing an Artificial Oxalate Operon and Vitreoscilla Hemoglobin Secretes Oxalic Acid and Solubilizes Rock Phosphate in Acidic Alfisols

OpenAIRE

Yadav, Kavita; Kumar, Chanchal; Archana, G.; Naresh Kumar, G.

2014-01-01

Oxalate secretion was achieved in Pseudomonas fluorescens ATCC 13525 by incorporation of genes encoding Aspergillus niger oxaloacetate acetyl hydrolase (oah), Fomitopsis plaustris oxalate transporter (FpOAR) and Vitreoscilla hemoglobin (vgb) in various combinations. Pf (pKCN2) transformant containing oah alone accumulated 19 mM oxalic acid intracellularly but secreted 1.2 mM. However, in the presence of an artificial oxalate operon containing oah and FpOAR genes in plasmid pKCN4, Pf (pKCN4) s...

Calcium fertilization increases the concentration of calcium in sapwood and calcium oxalate in foliage of red spruce

Science.gov (United States)

Kevin T. Smith; Walter C. Shortle; Jon H. Connolly; Rakesh Minocha; Jody Jellison

2009-01-01

Calcium cycling plays a key role in the health and productivity of red spruce forests in the northeastern US. A portion of the flowpath of calcium within forests includes translocation as Ca2+ in sapwood and accumulation as crystals of calcium oxalate in foliage. Concentrations of Ca in these tree tissues have been used as markers of...

Crystal structure representations for machine learning models of formation energies

Energy Technology Data Exchange (ETDEWEB)

Faber, Felix [Department of Chemistry, Institute of Physical Chemistry and National Center for Computational Design and Discovery of Novel Materials, University of Basel Switzerland; Lindmaa, Alexander [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping Sweden; von Lilienfeld, O. Anatole [Department of Chemistry, Institute of Physical Chemistry and National Center for Computational Design and Discovery of Novel Materials, University of Basel Switzerland; Argonne Leadership Computing Facility, Argonne National Laboratory, 9700 S. Cass Avenue Lemont Illinois 60439; Armiento, Rickard [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping Sweden

2015-04-20

We introduce and evaluate a set of feature vector representations of crystal structures for machine learning (ML) models of formation energies of solids. ML models of atomization energies of organic molecules have been successful using a Coulomb matrix representation of the molecule. We consider three ways to generalize such representations to periodic systems: (i) a matrix where each element is related to the Ewald sum of the electrostatic interaction between two different atoms in the unit cell repeated over the lattice; (ii) an extended Coulomb-like matrix that takes into account a number of neighboring unit cells; and (iii) an ansatz that mimics the periodicity and the basic features of the elements in the Ewald sum matrix using a sine function of the crystal coordinates of the atoms. The representations are compared for a Laplacian kernel with Manhattan norm, trained to reproduce formation energies using a dataset of 3938 crystal structures obtained from the Materials Project. For training sets consisting of 3000 crystals, the generalization error in predicting formation energies of new structures corresponds to (i) 0.49, (ii) 0.64, and (iii) 0.37eV/atom for the respective representations.

Oxalate-metabolising genes of the white-rot fungus Dichomitus squalens are differentially induced on wood and at high proton concentration.

Directory of Open Access Journals (Sweden)

Miia R Mäkelä

Full Text Available Oxalic acid is a prevalent fungal metabolite with versatile roles in growth and nutrition, including degradation of plant biomass. However, the toxicity of oxalic acid makes regulation of its intra- and extracellular concentration crucial. To increase the knowledge of fungal oxalate metabolism, a transcriptional level study on oxalate-catabolising genes was performed with an effective lignin-degrading white-rot fungus Dichomitus squalens, which has demonstrated particular abilities in production and degradation of oxalic acid. The expression of oxalic-acid decomposing oxalate decarboxylase (ODC and formic-acid decomposing formate dehydrogenase (FDH encoding genes was followed during the growth of D. squalens on its natural spruce wood substrate. The effect of high proton concentration on the regulation of the oxalate-catabolising genes was determined after addition of organic acid (oxalic acid and inorganic acid (hydrochloric acid to the liquid cultures of D. squalens. In order to evaluate the co-expression of oxalate-catabolising and manganese peroxidase (MnP encoding genes, the expression of one MnP encoding gene, mnp1, of D. squalens was also surveyed in the solid state and liquid cultures. Sequential action of ODC and FDH encoding genes was detected in the studied cultivations. The odc1, fdh2 and fdh3 genes of D. squalens showed constitutive expression, whereas ODC2 and FHD1 most likely are the main responsible enzymes for detoxification of high concentrations of oxalic and formic acids. The results also confirmed the central role of ODC1 when D. squalens grows on coniferous wood. Phylogenetic analysis revealed that fungal ODCs have evolved from at least two gene copies whereas FDHs have a single ancestral gene. As a conclusion, the multiplicity of oxalate-catabolising genes and their differential regulation on wood and in acid-amended cultures of D. squalens point to divergent physiological roles for the corresponding enzymes.

Acute oxalate nephropathy after ingestion of star fruit.

Science.gov (United States)

Chen, C L; Fang, H C; Chou, K J; Wang, J S; Chung, H M

2001-02-01

Acute oxalate nephropathy associated with ingestion of star fruit (carambola) has not been reported before. We report the first two cases. These patients developed nausea, vomiting, abdominal pain, and backache within hours of ingesting large quantities of sour carambola juice; then acute renal failure followed. Both patients needed hemodialysis for oliguric acute renal failure, and pathologic examinations showed typical changes of acute oxalate nephropathy. The renal function recovered 4 weeks later without specific treatment. Sour carambola juice is a popular beverage in Taiwan. The popularity of star fruit juice is not compatible with the rare discovery of star fruit-associated acute oxalate nephropathy. Commercial carambola juice usually is prepared by pickling and dilution processes that reduce oxalate content markedly, whereas pure fresh juice or mild diluted postpickled juice for traditional remedies, as used in our cases, contain high quantities of oxalate. An empty stomach and dehydrated state may pose an additional risk for development of renal injury. To avoid acute oxalate nephropathy, pure sour carambola juice or mild diluted postpickled juice should not be consumed in large amounts, especially on an empty stomach or in a dehydrated state.

Formation of the molecular crystal structure during the vacuum sublimation of paracetamol

Science.gov (United States)

Belyaev, A. P.; Rubets, V. P.; Antipov, V. V.; Bordei, N. S.

2015-04-01

The results from structural and thermal studies on the formation of molecular crystals during the vacuum sublimation of paracetamol from its vapor phase are given. It is established that the vapor-crystal phase transition proceeds in a complicated way as the superposition of two phase transitions: a first-order phase transition with a change in density, and a second-order phase transition with a change in ordering. It is shown that the latter is a smeared phase transition that proceeds with the formation of a pretransitional phase that is irreversibly dissipated during phase transformation, leading to the formation of crystals of the rhombic syngony. Data from differential scanning calorimetry and X-ray diffraction analysis are presented along with microphotographs.

The role of nanoparticulate agglomerates in TiO{sub 2} photocatalysis: degradation of oxalic acid

Energy Technology Data Exchange (ETDEWEB)

Ivanova, Irina [Leibniz Universitaet Hannover, Institut fuer Technische Chemie (Germany); Mendive, Cecilia B., E-mail: cbmendive@mdp.edu.ar [Universidad Nacional de Mar del Plata, Facultad de Ciencias Exactas y Naturales, Departamento de Química (Argentina); Bahnemann, Detlef [Leibniz Universitaet Hannover, Institut fuer Technische Chemie (Germany)

2016-07-15

The simultaneous bimodal study of the photocatalytic oxalic acid degradation by aqueous TiO{sub 2} suspensions revealed that particular systems possess the capacity to protect a certain amount of oxalic acid from oxidation, thus hindering, to some extent, the photocatalytic reaction. While measurements of the oxalic acid concentration in the bulk liquid phase indicated full photocatalytic degradation; in situ pH-stat measurements allowed the quantification of the amount of oxalic acid remaining in the part of the nanoparticulate agglomerates where light could apparently not access. An explanation for this phenomenon takes into account the possibility of the formation of TiO{sub 2} agglomerates in which these molecules are hidden from the effect of the light, thus being protected from photocatalytic degradation. Studies of different TiO{sub 2} materials with different particle sizes allowed a deeper exploration of this phenomenon. In addition, because this property of encapsulating pollutant molecules by photocatalytic systems is found to be a reversible phenomenon, P25 appears to be more convenient and advantageous as compared to the use of large surface area photocatalysts.Graphical AbstractFig.: Deaggregation of TiO{sub 2} particle agglomerates upon UV illumination.

Inhibition of calcium oxalate crystal deposition on kidneys of urolithiatic rats by Hibiscus sabdariffa L. extract.

Science.gov (United States)

Laikangbam, Reena; Damayanti Devi, M

2012-06-01

The present study aims at systematic evaluation of the calyces of Hibiscus sabdariffa to establish its scientific validity for anti-urolithiatic property using ethylene glycol-induced hyperoxaluria model in male albino rats. Administration of a mixture of 0.75% ethylene glycol and 2% ammonium chloride resulted in hyperoxaluria as well as increased renal excretion of calcium and phosphate. The decrease in the serum calcium concentration indicates an increased calcium oxalate formation. Supplementation of aqueous extract of H. sabdariffa at different doses (250, 500 and 750 mg/kg body weight) significantly lowered the deposition of stone-forming constituents in the kidneys and serum of urolithiatic rats. These findings have been confirmed through histological investigations. Results of in vivo genotoxicity testing showed no significant chromosomal aberrations in the bone marrow cells of ethylene glycol-induced rats. The plant extracts at the doses investigated induced neither toxic nor lethal effects and are safe. It can be concluded that the calyces of H. sabdariffa are endowed with anti-urolithiatic activity and do not have genotoxic effects. Thus, it can be introduced in clinical practices and medicine in the form of orally administered syrup after further investigations and clinical trials.

Serpula lacrymans, The Dry Rot Fungus and Tolerance Towards Copper-Based Wood Preservatives

DEFF Research Database (Denmark)

Hastrup, Anne Christine Steenkjær; Jensen, Bo; Clausen, Carol

2005-01-01

-rot fungi is thought to be due in part to oxalic acid production and accumulation. Oxalic acid has been implicated in copper tolerance by the formation of copper oxalate crystals. Twelve isolates of the dry rot fungus, S. lacrymans and four other brown rot species were evaluated for weight loss on wood...

New open-framework three-dimensional lanthanide oxalates containing as a template the diprotonated 1,2- or 1,3-diaminopropane

International Nuclear Information System (INIS)

Mohanu, A.; Brouca-Cabarrecq, C.; Trombe, J.C.

2006-01-01

Single crystals of three new open-framework lanthanide oxalates have been synthesized hydrothermally, in the presence of 1,2-diaminopropane, (C 3 N 2 H 12 )[Nd(H 2 O)(C 2 O 4 ) 2 ] 2 .3H 2 O I and (C 3 N 2 H 12 )[Yb(C 2 O 4 ) 2 ] 2 .5H 2 O II, or 1,3-diaminopropane (C 3 N 2 H 12 ) 2 [La 2 (C 2 O 4 ) 5 ].5H 2 O III. Their structures have been determined by X-ray diffraction data: I and III crystallize in the triclinic system, space group P-1, with a=7.8130(5)A, b=11.8800(6)A, c=12.9940(8)A, α=93.092(5) o , β=93.930(6) o , γ=108.359(5) o and a=11.6650(9)A, b=11.9240(6)A, c=13.2230(7)A, α=104.585(4) o , β=108.268(5) o , γ=111.132(5) o , respectively while II crystallizes in the orthorhombic system, space group F2dd, with a=8.7970(4)A, b=16.1550(8)A, c=32.170(2)A. The three-dimensional (3D) framework of these compounds is built up by the linkages of lanthanide atoms and the oxygen atoms of the bischelating oxalate ligands. Instead of four chelating oxalate units surrounding a lanthanide atom (I and II), both lanthanum atoms, in III, are surrounded by five chelating oxalate groups and that is new. In all the cases within the frame, are observed 8- and 12-membered channels where are localized the guest species, 1,2- or 1,3-diaminopropane cations and free water molecules. The ratio of the guest number (especially the diaminopropane) per 12-membered ring could tune the shape and the size of 12-membered channels: thus, the 12-membered channels, observed for I and II, have elliptical cross-section (5.5Ax11.4A and 5.2Ax9.5A) while those, observed for III, have nearly circular cross-section (9.1Ax9.5A). The lanthanide atoms are 8, 9 and 10-fold coordinated for Yb (II), Nd (I) and La (III), respectively

OXALATE MASS BALANCE DURING CHEMICAL CLEANING IN TANK 6F

Energy Technology Data Exchange (ETDEWEB)

Poirier, M.; Fink, S.

2011-07-22

The Savannah River Remediation (SRR) is preparing Tank 6F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRR personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 6F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate. Some conclusions from this work are: (1) Approximately 65% of the oxalate added as oxalic acid was removed with the decanted liquid. (2) Approximately 1% of the oxalate (added to the tank as oxalic acid) formed precipitates with compounds such as nickel, manganese, sodium, and iron (II), and was dissolved with nitric acid. (3) As much as 30% of the oxalate may have decomposed forming carbon dioxide. The balance does not fully account for all the oxalate added. The offset represents the combined uncertainty in the analyses and sampling.

Effects of reactive Mn(III)-oxalate complexes on structurally intact plant cell walls

Science.gov (United States)

Summering, J. A.; Keiluweit, M.; Goni, M. A.; Nico, P. S.; Kleber, M.

2011-12-01

Lignin components in the in plant litter are commonly assumed to have longer residence times in soil than many other compounds, which are supposedly, more easily degradable. The supposed resistance of lignin compounds to decomposition is generally attributed to the complex chain of biochemical steps required to create footholds in the non-porous structure of ligno-cellulose in cell walls. Interestingly, Mn(III) complexes have shown the ability to degrade ligno-cellulose. Mn(III) chelated by ligands such as oxalate are soluble oxidizers with a high affinity for lignin structures. Here we determined (i) the formation and decay kinetics of the Mn(III)-oxalate complexes in aqueous solution and (ii) the effects that these complexes have on intact ligno-cellulose. UV/vis spectroscopy and iodometric titrations confirmed the transient nature of Mn(III)-oxalate complexes with decay rates being in the order of hours. Zinnia elegans tracheary elements - a model ligno-cellulose substrate - were treated with Mn(III)-oxalate complexes in a newly developed flow-through reactor. Soluble decomposition products released during the treatment were analyzed by GC/MS and the degree of cell integrity was measured by cell counts, pre- and post-treatment counts indicate a decrease in intact Zinnia elegans as a result of Mn(III)-treatment. GC/MS results showed the release of a multitude of solubilized lignin breakdown products from plant cell walls. We conclude that Mn(III)-oxalate complexes have the ability to lyse intact plant cells and solubilize lignin. Lignin decomposition may thus be seen as resource dependent, with Mn(III) a powerful resource that should be abundant in terrestrial characterized by frequent redox fluctuations.

Quantitative Mineralogical Composition of Calculi and Urine Abnormalities for Calcium Oxalate Stone Formers: A Single-Center Results.

Science.gov (United States)

Kustov, Andrey V; Strelnikov, Alexander I

2017-12-26

The paper focuses on the relationship of risk factors and metabolic disorders with mineralogical composition of calculi, age and gender of calcium oxalate stone formers. Stone mineralogical composition, 24 hour biochemistry and pH-profile of urine were examined for sixty four stone formers using powder X-ray diffraction, spectrophotometric and potentiometric techniques. The analysis indicated that 44 % of calculi were composed of pure calcium oxalate monohydrate, whereas other 56 % contained both monohydrate and dihydrate or usually their mixtures with hydroxyl apatite. Hypocitraturia, hypercalciuria and hyperuricosuria were identified as the most frequent disorders. Patients with pure calcium oxalate stones and calcium oxalate mixed with apatite revealed different patterns including age, acid-base balance of urine, calcium, citrate excretion etc. Our results demonstrate that most patients simultaneously reveal several risk factors. The special attention should be paid to normalize the daily citrate, calcium and urate excretion. High risk patients, such as postmenopausal females or stone formers with a high apatite content require a specific metabolic evaluation towards in highlighting abnormalities associated with stone formation.

Calcium oxalate contribution to calcium cycling in forests of contrasting nutrient status

Science.gov (United States)

Dauer, Jenny M.; Perakis, Steven S.

2014-01-01

Calcium oxalate (Ca oxalate) is an insoluble biomineral that forms in plants and fungi, and occurs in soils across many types of ecosystems. Assessing how Ca oxalate may shape ecosystem Ca cycling requires information on the distribution of Ca oxalate among plant biomass, detritus, and mineral soil, and how it varies with ecosystem Ca status. We compared two Douglas-fir forests of contrasting ecosystem Ca availability, and found that Ca oxalate was partitioned similarly among plant biomass, detritus and mineral soil major ecosystem compartments at both sites, and total pools of Ca oxalate were greater in the high-Ca forest. However, the proportional importance of Ca oxalate was greater in the low-Ca than high-Ca forest (18% versus 4% of actively cycling ecosystem Ca, respectively). And calcium oxalate in mineral soil, which is of particular interest as a potential long-term Ca reservoir, was a larger portion of total available Ca (exchangeable Ca plus Ca oxalate Ca) in the low-Ca site than the high-Ca site (9% versus 1% of available soil Ca, respectively). Calcium oxalate was the dominant form of Ca returned from plants to soil as leaf litterfall at the high-Ca site, yet calcium oxalate disappeared rapidly from decomposing litter (0.28 yr−1 or faster) at both sites. We conclude that accumulation of Ca oxalate in forest ecosystems appears most closely related to overall Ca supply for live biomass pools, and that the accumulation of Ca oxalate in forest floor and mineral soil is limited by rapid microbial degradation of putatively unavailable Ca oxalate.

Study of lithium extraction from brine water, Bledug Kuwu, Indonesia by the precipitation series of oxalic acid and carbonate sodium

Science.gov (United States)

Sulistiyono, Eko; Lalasari, Latifa Hanum; Mayangsari, W.; Prasetyo, A. B.

2018-05-01

Lithium is one of the key elements in the development of batteries for electric car applications. Currently, the resources of the world's lithium are derived from brine water and lithium mineral based on spodumene rock. Indonesia which is located in the area of the ring of fire, has potential brine water resources in some area, such as brine water from Bledug Kuwu, Central Java that used in this research. The purposes of this research are to characterize brine water, Bledug Kuwu and to investigate the influence of chemical solvents on Li, Na, K, Ca, Mg, Al, B ion precipitation from brine water. This research was done with 2 times the process of chemical precipitation that runs series as follows: 5 liters of brine water were chemically precipitated using 400 ml of 12.43 N oxalic acid and followed by chemical precipitation using 400 mL of 7.07 N sodium carbonate solutions. Evaporation and filtration processes were also done twice in an effort to separate white precipitate and filtrate. The filtrate was analyzed by ICP-OES and white precipitates (salts) were analyzed by SEM, XRD, and XRF. The result shows that oxalate precipitation process extracted 32.24% Al, 23.42% B, 22.43% Ca, 14.26% Fe, 3.21 % K, 9.86% Na and 14.26% Li, the following process by carbonate precipitation process extracted 98.86% Mg, 73% Ca, 22.53% Li, 82.04% Al, 14.38% B, 12.50% K, 2.27% Na. There is 63.21% lithium is not extracted from the series process. The SEM analysis shows that the structure of granules on the precipitated salts by oxalic acid form gentle cubic-shaped solid. In the other hand, oxalate precipitation followed by sodium carbonate has various particle sizes and the shape of crystals is fragments, prism and cube look like magnesium carbonate, calcium chloride, and calcite's crystal respectively. This is in accordance with XRD analysis that phases of whewellite (CaC2O4.H2O), disodium oxalate (Na2C2O4), magnesite (MgCO3), calcium lithium aluminum (Al1.19 Ca1Li0.81), dolomite (CaCO3

Crystal size effect on the electrochemical oxidation of formate on carbon-supported palladium nanoparticles

International Nuclear Information System (INIS)

Santos, Rayana Marcela Izidoro da Silva; Nakazato, Roberto Zenhei; Ciapina, Eduardo Goncalves

2016-01-01

Full text: The electrochemical oxidation of formate in alkaline electrolytes has emerged an a promising anodic reaction in the Direct Formate Fuel Cells[1]. Although palladium is considered to be one of the best electro catalyst for the oxidation of formate, important structure-activity relationships are still not understood. In the present work, we investigated the effect of the size of the palladium crystals in the electrochemical oxidation of formate in 0.1 mol L -1 KOH. Carbon-supported palladium nanoparticles (Pd/C) were prepared by chemical reduction of palladium (II) chloride in aqueous media by sodium borohydride in the presence of varying quantities of sodium citrate in the reaction media to obtain metallic crystals with distinct sizes. Analysis of the X-ray diffraction profile revealed the presence of palladium crystals in the range of 6 to 19 nm. Potentiostatic oxidation of formate on the distinct Pd/C samples revealed a volcano-like dependence of the specific activity with the size of the palladium crystals, presenting the highest activity for crystals around 7.5 nm. Reference: [1] A.M. Bartrom, J.L. Haan, The direct formate fuel cell with an alkaline anion exchange membrane, J. Power Sources. 214 (2012) 68-74. (author)

Radiolysis of titanium potassium oxalate in aqueous solution. [. gamma. rays

Energy Technology Data Exchange (ETDEWEB)

Bundo, Y; Ono, I [Industrial Research Inst. of Kanagawa Prefecture, Yokohama (Japan); Ogawa, T

1975-01-01

The dissolution state of titanium potassium oxalate in aqueous solution is different according to the pH. The yellowish brown titanium complex produced by the reaction of titanium potassium oxalate and hydrogen peroxide seems to be different in its structure according to the pH. Considering these points, gamma-ray irradiation was carried out on the sample by dissolving titanium potassium oxalate in purified water under the conditions of oxygen saturation and nitrogen saturation, and the relation between irradiation dose and the production of titanium complex was determined. On the basis of the experimental result, the mechanism of forming hydrogen peroxide was presumed. The radiation source used was 2,000 Ci of /sup 60/Co. For photometric analysis, a 139 type photoelectric spectrophotometer of Hitachi Ltd. was used. From the experimental results, in neutral water, titanium potassium oxalate exists in the state that two oxalic acid ions are coordinated to titanyl ion, while in case of the pH lowered by the addition of sulfuric acid, it can exist in the state that one oxalic acid ion is coordinated to titanyl ion. The yield of hydrogen peroxide produced by irradiating titanium potassium oxalate aqueous solution with gamma-ray is the sum of the molecular product from water and the radiolysis product from titanium potassium oxalate.

Effect of heat treatment on the structure of incorporated oxalate species and photoluminescent properties of porous alumina films formed in oxalic acid

Science.gov (United States)

Vrublevsky, I.; Jagminas, A.; Hemeltjen, S.; Goedel, W. A.

2008-09-01

The present work focuses on the use of IR spectroscopy and photoluminescence spectral measurements for studying the treatment temperature effect on the compositional and luminescent properties of oxalic acid alumina films. In line with the recent researches we have also found that heat treatment of porous alumina films formed in oxalic acid leads to considerable changes in their photoluminescence properties: upon annealing the intensity of photoluminescence (PL) increases reaching a maximum at the temperature of around 500 °C and then decreases. IR spectra of as-grown and heat-treated films have proved that PL emission in the anodic alumina films is related with the state of 'structural' oxalate species incorporated in the oxide lattice. These results allowed us to conclude that PL behavior of oxalic acid alumina films can be explained through the concept of variations in the bonding molecular orbitals of incorporated oxalate species including σ- and π-bonds.

Oxalic acid as a heterogeneous ice nucleus in the upper troposphere and its indirect aerosol effect

Directory of Open Access Journals (Sweden)

B. Zobrist

2006-01-01

Full Text Available Heterogeneous ice freezing points of aqueous solutions containing various immersed solid dicarboxylic acids (oxalic, adipic, succinic, phthalic and fumaric have been measured with a differential scanning calorimeter. The results show that only the dihydrate of oxalic acid (OAD acts as a heterogeneous ice nucleus, with an increase in freezing temperature between 2 and 5 K depending on solution composition. In several field campaigns, oxalic acid enriched particles have been detected in the upper troposphere with single particle aerosol mass spectrometry. Simulations with a microphysical box model indicate that the presence of OAD may reduce the ice particle number density in cirrus clouds by up to ~50% when compared to exclusively homogeneous cirrus formation without OAD. Using the ECHAM4 climate model we estimate the global net radiative effect caused by this heterogeneous freezing to result in a cooling as high as −0.3 Wm−2.

Do carboximide–carboxylic acid combinations form co-crystals? The role of hydroxyl substitution on the formation of co-crystals and eutectics

Directory of Open Access Journals (Sweden)

Ramanpreet Kaur

2015-05-01

Full Text Available Carboxylic acids, amides and imides are key organic systems which provide understanding of molecular recognition and binding phenomena important in biological and pharmaceutical settings. In this context, studies of their mutual interactions and compatibility through co-crystallization may pave the way for greater understanding and new applications of their combinations. Extensive co-crystallization studies are available for carboxylic acid/amide combinations, but only a few examples of carboxylic acid/imide co-crystals are currently observed in the literature. The non-formation of co-crystals for carboxylic acid/imide combinations has previously been rationalized, based on steric and computed stability factors. In the light of the growing awareness of eutectic mixtures as an alternative outcome in co-crystallization experiments, the nature of various benzoic acid/cyclic imide combinations is established in this paper. Since an additional functional group can provide sites for new intermolecular interactions and, potentially, promote supramolecular growth into a co-crystal, benzoic acids decorated with one or more hydroxyl groups have been systematically screened for co-crystallization with one unsaturated and two saturated cyclic imides. The facile formation of an abundant number of hydroxybenzoic acid/cyclic carboximide co-crystals is reported, including polymorphic and variable stoichiometry co-crystals. In the cases where co-crystals did not form, the combinations are shown invariably to result in eutectics. The presence or absence and geometric disposition of hydroxyl functionality on benzoic acid is thus found to drive the formation of co-crystals or eutectics for the studied carboxylic acid/imide combinations.

Neurotoxic effects of carambola in rats: the role of oxalate.

Science.gov (United States)

Chen, Chien-Liang; Chou, Kang-Ju; Wang, Jyh-Seng; Yeh, Jeng-Hsien; Fang, Hua-Chang; Chung, Hsiao-Min

2002-05-01

Carambola (star fruit) has been reported to contain neurotoxins that cause convulsions, hiccups, or death in uremic patients, and prolong barbiturate-induced sleeping time in rats. The constituent responsible for these effects remains uncertain. Carambola contains a large quantity of oxalate, which can induce depression of cerebral function and seizures. This study was conducted to investigate the role of oxalate in carambola toxicity in rats. The effects on barbiturate-induced sleeping time and death caused by intraperitoneal administration of carambola juice were observed in Sprague-Dawley rats. To obtain a dose-dependent response curve and evaluate the lethal dose, rats were treated with serial amounts of pure carambola juice diluted with normal saline in a volume of 1:1. To test the role of oxalate in the neurotoxic effect of carambola, either 5.33 g/kg carambola after oxalate removal or 5.33 g/kg of pure carambola juice diluted with normal saline were administered intraperitoneally, while the control group was given normal saline before pentobarbital injection. The effects of carambola and oxalate-removed carambola on barbiturate-induced sleeping time were compared with those of saline. To assess the lethal effect of oxalate in carambola, we gave rats chemical oxalate at comparable concentrations to the oxalate content of carambola. Carambola juice administration prolonged barbiturate-induced sleeping time in a dose-dependent manner. The sleeping time of rats that received normal saline and 1.33 g/kg, 2.67 g/kg, 5.33 g/kg, and 10.67 g/kg of carambola juice were 66 +/- 16.6, 93.7 +/- 13.4, 113.3 +/- 11.4, 117.5 +/- 29.0, and 172.5 +/- 38.8 minutes, respectively. The three higher-dose groups had longer sleeping times than controls (p carambola juice. Four of eight rats in the 10.67-g/kg group and all rats in the 21.33 g/kg and chemical oxalate groups died after seizure. Lethal doses of carambola juice were rendered harmless by the oxalate removal procedure

Relating mechanical properties and chemical bonding in an inorganic-organic framework material: a single-crystal nanoindentation study.

Science.gov (United States)

Tan, Jin Chong; Furman, Joshua D; Cheetham, Anthony K

2009-10-14

We report the application of nanoindentation and atomic force microscopy to establish the fundamental relationships between mechanical properties and chemical bonding in a dense inorganic-organic framework material: Ce(C(2)O(4))(HCO(2)), 1. Compound 1 is a mixed-ligand 3-D hybrid which crystallizes in an orthorhombic space group, in which its three basic building blocks, i.e. the inorganic metal-oxygen-metal (M-O-M) chains and the two organic bridging ligands, (oxalate and formate) are all oriented perpendicular to one another. This unique architecture enabled us to decouple the elastic and plastic mechanical responses along the three primary axes of a single crystal to understand the contribution associated with stiff vs compliant basic building blocks. The (001)-oriented facet that features rigid oxalate ligands down the c-axis exhibits the highest stiffness and hardness (E approximately 78 GPa and H approximately 4.6 GPa). In contrast, the (010)-oriented facet was found to be the most compliant and soft (E approximately 43 GPa and H approximately 3.9 GPa), since the formate ligand, which is the more compliant building block within this framework, constitutes the primary linkages down the b-axis. Notably, intermediate stiffness and hardness (E approximately 52 GPa and H approximately 4.1 GPa) were measured on the (100)-oriented planes. This can be attributed to the Ce-O-Ce chains that zigzag down the a-axis (Ce...Ce metal centers form an angle of approximately 132 degrees) and also the fact that the 9-coordinated CeO(9) polyhedra are expected to be geometrically more compliant. Our results present the first conclusive evidence that the crystal orientation dominated by inorganic chains is not necessarily more robust from the mechanical properties standpoint. Rigid organic bridging ligands (such as oxalate), on the other hand, can be used to produce greater stiffness and hardness properties in a chosen crystallographic orientation. This study demonstrates that

Two novel 3-D bismuth oxalates with organic amines protruding in channels

International Nuclear Information System (INIS)

Yu Xiaohong; Zhang Hanhui; Cao Yanning; Hu Zhongjian; Chen Yiping; Wang Zhen

2006-01-01

Two novel 3-D oxalate-containing bismuth compounds of formula (C 3 N 2 H 5 ) 2 [Bi 2 (C 2 O 4 ) 4 (H 2 O) 2 ].2H 2 O 1 and [NH(C 2 H 5 ) 3 ][Bi 3 (C 2 O 4 ) 5 ] 2 were obtained by hydrothermal synthesis and characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic P2/n space group with a=9.7541(13)A, b=17.7404(15)A, c=14.6321(6)A, β=97.280(3) o , Z=4, R 1 =0.0340 and wR 2 =0.0766 for unique 4734 reflections I>2σ(I). Compound 2 belongs to the orthorhombic Pbcn space group with a=14.803(4)A, b=19.783(7)A, c=8.202(2)A, Z=4, R 1 =0.0222 and wR 2 =0.0568 for unique 2472 reflections I>2σ(I). The Bi III centers have nine-fold coordination for 1 and eight-fold for 2 with the Bi atoms in distorted monocapped square antiprism and distorted dodecahedron, respectively. And oxalate ligands adopt different coordination modes: bidentate for 1, bidentate and tricoordinate for 2. Compounds 1 and 2 are both 3-D open-framework structures containing channels with guest molecules. These two compounds exhibit intense blue luminescence with the emission peaks at 419nm for 1 and 442nm for 2, respectively, in the solid state at room temperature. These compounds with novel structural frameworks could be useful in the field of photoactive materials

Tris(bipyridineMetal(II-Templated Assemblies of 3D Alkali-Ruthenium Oxalate Coordination Frameworks: Crystal Structures, Characterization and Photocatalytic Activity in Water Reduction

Directory of Open Access Journals (Sweden)

Alla Dikhtiarenko

2016-02-01

Full Text Available A series of 3D oxalate-bridged ruthenium-based coordination polymers with the formula of {[ZII(bpy3][MIRu(C2O43]}n (ZII = Zn2+ (1, Cu2+ (3, 4, Ru2+ (5, 6, Os2+ (7, 8; MI = Li+, Na+; bpy = 2,2’-bipyridine and {[ZnII(bpy3](H2O[LiRu(C2O43]}n (2 has been synthesized at room temperature through a self-assembly reaction in aqueous media and characterized by single-crystal and powder X-ray diffraction, elemental analysis, infrared and diffuse reflectance UV–Vis spectroscopy and thermogravimetric analysis. The crystal structures of all compounds comprise chiral 3D honeycomb-like polymeric nets of the srs-type, which possess triangular anionic cages where [ZII(bpy3]2+ cationic templates are selectively embedded. Structural analysis reveals that the electronic configuration of the cationic guests is affected by electrostatic interaction with the anionic framework. Moreover, the MLCT bands gaps values for 1–8 can be tuned in a rational way by judicious choice of [ZII(bpy3]2+ guests. The 3D host-guest polymeric architectures can be used as self-supported heterogeneous photocatalysts for the reductive splitting of water, exhibiting photocatalytic activity for the evolution of H2 under UV light irradiation.

Fast Formation of Opal-like Columnar Colloidal Crystals

NARCIS (Netherlands)

van der Beek, D.; Radstake, P.B.; Petukhov, A.V.; Lekkerkerker, H.N.W.

2007-01-01

We demonstrate that highly polydisperse colloidal gibbsite platelets easily form an opal-like columnar crystal with striking iridescent Bragg reflections. The formation process can be accelerated by orders of magnitude under a centrifugation force of 900g without arresting the system in a disordered

Crystal structure and spectroscopic behavior of synthetic novgorodovaite Ca2(C2O4)Cl2·2H2O and its twinned triclinic heptahydrate analog

Science.gov (United States)

Piro, Oscar E.; Echeverría, Gustavo A.; González-Baró, Ana C.; Baran, Enrique J.

2018-02-01

Synthetic novgorodovaite analog Ca2(C2O4)Cl2·2H2O is identical to its natural counterpart. It crystallizes in the monoclinic I2/ m space group with a = 6.9352(3), b = 7.3800(4), c = 7.4426(3) Å, β = 94.303(4)°, V = 379.85(3) Å3 and Z = 2. The heptahydrate analog, Ca2(C2O4)Cl2·7H2O, crystallizes as triclinic twins in the P \\overline{1} space group with a = 7.3928(8), b = 8.9925(4), c = 10.484(2) Å, α = 84.070(7), β = 70.95(1), γ = 88.545(7)°, V = 655.3(1) Å3 and Z = 2. The crystal packing of both calcium oxalate-chloride double salts favors the directional bonding of oxalate, C2O4 2-, ligands to calcium ions as do other related calcium oxalate minerals. The π-bonding between C and O atoms of the C2O4 2- oxalate group leaves sp 2-hydridised orbitals of the oxygen atoms available for bonding to Ca. Thus, the Ca-O bonds in both calcium oxalate-chloride double salts are directed so as to lie in the plane of the oxalate group. This behavior is reinforced by the short O···O distances between the oxygens attached to a given carbon atom, which favors them bonding to a shared Ca atom in bidentate fashion. Strong bonding in the plane of the oxalate anion and wide spacing perpendicular to that plane due to repulsion between oxalate π-electron clouds gives rise to a polymerized structural units which are common to both hydrates, explaining the nearly equal cell constants 7.4 Å which are defined by the periodicity of Ca-oxalate chains in the framework (monoclinic b ≈ triclinic a). When compared with novgorodovaite, the higher water content of Ca2(C2O4)Cl2·7H2O leads to some major differences in their structures and ensuing physical properties. While novgorodovaite has a three-dimensional framework structure, in the higher hydrate, the highly polar water molecules displace chloride ions from the calcium coordination sphere and surround them through OwH···Cl hydrogen bonds. As a result, polymerization in Ca2(C2O4)Cl2·7H2O solid is limited to the formation

Isolation and some characteristics of anaerobic oxalate-degrading bacteria from the rumen.

OpenAIRE

Dawson, K A; Allison, M J; Hartman, P A

1980-01-01

Obligately anaerobic oxalate-degrading bacteria were isolated from an enriched population of rumen bacteria in an oxalate-containing medium that had been depleted of other readily metabolized substrates. These organisms, which are the first reported anaerobic oxalate degraders isolated from the rumen, were gram negative, nonmotile rods. They grew in a medium containing sodium oxalate, yeast extract, cysteine, and minerals. The only substrate that supported growth was oxalate. Growth was direc...

A new approach to study cadmium complexes with oxalic acid in soil solution.

Science.gov (United States)

Dytrtová, Jana Jaklová; Jakl, Michal; Sestáková, Ivana; Zins, Emilie-Laure; Schröder, Detlef; Navrátil, Tomáš

2011-05-05

This study presents a new analytical approach for the determination of heavy metals complexed to low-molecular-weight-organic acids in soil solutions, which combines the sensitivity of differential pulse anodic stripping voltammetry (DPASV) with the molecular insight gained by electrospray ionization mass spectrometry (ESI-MS). The combination of these analytical methods allows the investigation of such complexes in complex matrixes. On the voltammograms of the soil solutions, in addition to the expected complexes of oxalic acid with cadmium and lead, respectively, also peaks belonging to mixed complexes of cadmium, lead, and oxalic acid (OAH(2)) were observed. In order to verify the possible formation of complexes with OAH(2), aqueous solutions of OAH(2) with traces of Cd(II) were investigated as model systems. Signals corresponding to several distinct molecular complexes between cadmium and oxalic acid were detected in the model solutions using negative-ion ESI-MS, which follow the general formula [Cd(n)(X,Y)((2n+1))](-), where n is the number of cadmium atoms, X=Cl(-), and Y=OAH(-). Some of these complexes were also identified in the ESI mass spectra taken from the soil solutions. Copyright © 2011 Elsevier B.V. All rights reserved.

A new approach to study cadmium complexes with oxalic acid in soil solution

International Nuclear Information System (INIS)

Jaklova Dytrtova, Jana; Jakl, Michal; Sestakova, Ivana; Zins, Emilie-Laure; Schroeder, Detlef; Navratil, Tomas

2011-01-01

This study presents a new analytical approach for the determination of heavy metals complexed to low-molecular-weight-organic acids in soil solutions, which combines the sensitivity of differential pulse anodic stripping voltammetry (DPASV) with the molecular insight gained by electrospray ionization mass spectrometry (ESI-MS). The combination of these analytical methods allows the investigation of such complexes in complex matrixes. On the voltammograms of the soil solutions, in addition to the expected complexes of oxalic acid with cadmium and lead, respectively, also peaks belonging to mixed complexes of cadmium, lead, and oxalic acid (OAH 2 ) were observed. In order to verify the possible formation of complexes with OAH 2 , aqueous solutions of OAH 2 with traces of Cd(II) were investigated as model systems. Signals corresponding to several distinct molecular complexes between cadmium and oxalic acid were detected in the model solutions using negative-ion ESI-MS, which follow the general formula [Cd n (X,Y) (2n+1) ] - , where n is the number of cadmium atoms, X = Cl - , and Y = OAH - . Some of these complexes were also identified in the ESI mass spectra taken from the soil solutions.

A new approach to study cadmium complexes with oxalic acid in soil solution

Energy Technology Data Exchange (ETDEWEB)

Jaklova Dytrtova, Jana, E-mail: dytrtova@uochb.cas.cz [Institute of Organic Chemistry and Biochemistry of the AS CR, v.v.i., Flemingovo namesti 2, 16610 Prague 6 (Czech Republic); Jakl, Michal [Department of Agro-Environmental Chemistry and Plant Nutrition, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences, Kamycka 129, 16521 Prague - Suchdol (Czech Republic); Sestakova, Ivana [J. Heyrovsky Institute of Physical Chemistry of the AS CR, v.v.i., Dolejskova 3, 182 23 Prague 8 (Czech Republic); Zins, Emilie-Laure; Schroeder, Detlef [Institute of Organic Chemistry and Biochemistry of the AS CR, v.v.i., Flemingovo namesti 2, 16610 Prague 6 (Czech Republic); Navratil, Tomas [J. Heyrovsky Institute of Physical Chemistry of the AS CR, v.v.i., Dolejskova 3, 182 23 Prague 8 (Czech Republic)

2011-05-05

This study presents a new analytical approach for the determination of heavy metals complexed to low-molecular-weight-organic acids in soil solutions, which combines the sensitivity of differential pulse anodic stripping voltammetry (DPASV) with the molecular insight gained by electrospray ionization mass spectrometry (ESI-MS). The combination of these analytical methods allows the investigation of such complexes in complex matrixes. On the voltammograms of the soil solutions, in addition to the expected complexes of oxalic acid with cadmium and lead, respectively, also peaks belonging to mixed complexes of cadmium, lead, and oxalic acid (OAH{sub 2}) were observed. In order to verify the possible formation of complexes with OAH{sub 2}, aqueous solutions of OAH{sub 2} with traces of Cd(II) were investigated as model systems. Signals corresponding to several distinct molecular complexes between cadmium and oxalic acid were detected in the model solutions using negative-ion ESI-MS, which follow the general formula [Cd{sub n}(X,Y){sub (2n+1)}]{sup -}, where n is the number of cadmium atoms, X = Cl{sup -}, and Y = OAH{sup -}. Some of these complexes were also identified in the ESI mass spectra taken from the soil solutions.

Optimized Pyroelectric Vidicon Thermal Imager. Volume II. Improper Ferroelectric Crystal Growth.

Science.gov (United States)

1980-09-01

4.2.1 Apparatus .......................... 77 4.2.2 Growth from Acidic Media .................o 78 4.2.3 Hydrothermal Growth in Basic Media ...... 99...method of hydrothermal growth was examined using both acidic and basic solvents. (1) Standard Composition Our standard composition was derived from... Acid 10 Good, well formed crystals. Acrylic Acid 10 Very good, clear crystals. Glycine 10 Poor crystals. Oxalic Acid 10 Precipitation of calcium and

Interaction of Celestine Concentrate and Reagent Grade SrSO4 with Oxalate Solutions

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Abdullah Obut

2012-12-01

Full Text Available The interaction of reagent grade strontium sulphate and celestine concentrate with aqueous solutions of oxalic acid, sodiumoxalate and ammonium oxalate for the production of strontium carbonate were investigated for different oxalate compound:SrSO4 moleratios and reaction times using x-ray diffraction analysis and dissolution tests. Under the same experimental conditions, it was foundthat aqueous oxalic acid and sodium oxalate solutions had no or little effect on reagent grade strontium sulphate or celestineconcentrate, but aqueous ammonium oxalate solution converted them into strontium oxalate hydrate. Strontium carbonate was obtainedat conversion ratios of 74.7% for the celestine concentrate and 84.6 % for the reagent grade strontium sulphate by the decompositionof the obtained strontium oxalate hydrate at 600 °C under air atmosphere.

Crystal Macropattern Development in Prunus serotina (Rosaceae, Prunoideae) Leaves

OpenAIRE

LERSTEN, NELS R.; HORNER, HARRY T.

2006-01-01

• Background and Aims Prunus, subgenus Padus, exhibits two completely different calcium oxalate crystal macropatterns in mature leaves. Foliar macropattern development has been described previously in P. virginiana, representing one version. Prunus serotina, in the group exhibiting the second macropattern, is described here. The goal was to describe developmental details for comparison with P. virginiana, and to extend the sparse current knowledge of crystal macropatterns.

A neodymium(III)-ammonium complex involving oxalate and carbonate ligands: (NH4)2[Nd2(C2O4)3(CO3)(H2O)].H2O.

Science.gov (United States)

Trombe, Jean-Christian; Galy, Jean; Enjalbert, Renée

2002-10-01

The title compound, diammonium aqua-mu-carbonato-tri-mu-oxalato-dineodymium(III) hydrate, (NH(4))(2)[Nd(2)(CO(3))(C(2)O(4))(3)(H(2)O)].H(2)O, involving the two ligands oxalate and carbonate, has been prepared hydrothermally as single crystals. The Nd atoms form a tetranuclear unit across the inversion centre at (1/2, 1/2, 1/2). Starting from this tetranuclear unit, the oxalate ligands serve to develop a three-dimensional network. The carbonate group acts as a bis-chelating ligand to two Nd atoms, and is monodentate to a third Nd atom. The oxalate groups are all bis-chelating. The two independent Nd atoms are ninefold coordinated and the coordination polyhedron of these atoms is a distorted monocapped antiprism.

Influence of additives on the structure and microstructure of lanthanides and actinides oxalates

International Nuclear Information System (INIS)

Haidon, Blaise; Vitart, Anne-Lise; Rivenet, Murielle; Arab-Chapelet, Benedicte; Roussel, Pascal; Delahaye, Thibaud; Grandjean, Stephane; Abraham, Francis

2015-07-01

Oxalic conversion is a well-known process in the nuclear industry where it is used for precipitating plutonium as an oxalate thereafter calcinated into an oxide. As there is a strong relationship between the morphology of the oxalate precursor and that of the resulting oxide, it is of interest to control the oxalate structure and microstructure during the precipitation step. The influence of additives on the precipitation of neodymium (III) oxalates, non-radioactive analogs of actinides (III) oxalates, was explored. With the use of nitrilotri-methylphosphonic acid (NTMP), the structure and microstructure of the neodymium oxalates are different from that obtained without additive. (authors)

Can Randall's plug composed of calcium oxalate form via the free particle mechanism?

Science.gov (United States)

Grases, F; Söhnel, O

2017-09-08

The likelihood of a Randall's plug composed of calcium oxalate monohydrate (COM) forming by the free particle mechanism in a model of kidney with a structure recently described by Robertson was examined at the most favourable conditions for the considered mechanism. The Robertson model of the kidney is used in the following development. The classical theory of crystallization was used for calculations. Initial COM nuclei were assumed to form at the beginning of the ascending loop of Henle where the supersaturation with respect to COM has been shown to reach the threshold level for spontaneous nucleation. Nucleation proceeds by a heterogeneous mechanism. The formed particles are transported in the nephron by a laminar flow of liquid with a parabolic velocity profile. Particles travel with a velocity dependent on their position in the cross-section of the nephron assumed to be straight tubule with smooth walls and without any sharp bends and kinks. These particles move faster with time as they grow as a result of being surrounded by the supersaturated liquid. Individual COM particles (crystals) can reach maximum diameter of 5.2 × 10 -6  m, i.e. 5.2 μm, at the opening of the CD and would thus always be washed out of the CD into the calyx regardless of the orientation of the CD. Agglomeration of COM crystals forms a fractal object with an apparent density lower than the density of solid COM. The agglomerate that can block the beginning of the CD is composed of more crystals than are available even during crystaluria. Moreover the settling velocity of agglomerate blocking the opening of the CD is lower than the liquid flow and thus such agglomerate would be washed out even from upward-draining CD. The free particle mechanism may be responsible for the formation of a Randall's plug composed by COM only in specific infrequent cases such as an abnormal structure of kidney. Majority of incidences of Randall's plug development by COM are caused by mechanism different

Oxaloacetate hydrolase, the C-C bond lyase of oxalate secreting fungi

NARCIS (Netherlands)

Han, Y.; Joosten, H.J.; Niu, W.; Zhao, Z.; Mariano, P.S.; McCalman, M.; Kan, van J.; Schaap, P.J.; Dunaway-Mariano, D.

2007-01-01

Oxalate secretion by fungi is known to be associated with fungal pathogenesis. In addition, oxalate toxicity is a concern for the commercial application of fungi in the food and drug industries. Although oxalate is generated through several different biochemical pathways, oxaloacetate

A paracrine mechanism involving renal tubular cells, adipocytes and macrophages promotes kidney stone formation in a simulated metabolic syndrome environment.

Science.gov (United States)

Zuo, Li; Tozawa, Keiichi; Okada, Atsushi; Yasui, Takahiro; Taguchi, Kazumi; Ito, Yasuhiko; Hirose, Yasuhiko; Fujii, Yasuhiro; Niimi, Kazuhiro; Hamamoto, Shuzo; Ando, Ryosuke; Itoh, Yasunori; Zou, Jiangang; Kohri, Kenjiro

2014-06-01

We developed an in vitro system composed of renal tubular cells, adipocytes and macrophages to simulate metabolic syndrome conditions. We investigated the molecular communication mechanism of these cells and their involvement in kidney stone formation. Mouse renal tubular cells (M-1) were cocultured with adipocytes (3T3-L1) and/or macrophages (RAW264.7). Calcium oxalate monohydrate crystals were exposed to M-1 cells after 48-hour coculture and the number of calcium oxalate monohydrate crystals adherent to the cells was quantified. The expression of cocultured medium and M-1 cell inflammatory factors was analyzed by enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively. The inflammatory markers MCP-1, OPN and TNF-α were markedly up-regulated in cocultured M-1 cells. OPN expression increased in M-1 cells cocultured with RAW264.7 cells while MCP-1 and TNF-α were over expressed in M-1 cells cocultured with 3T3-L1 cells. Coculturing M-1 cells simultaneously with 3T3-L1 and RAW264.7 cells resulted in a significant increase in calcium oxalate monohydrate crystal adherence to M-1 cells. Inflammatory cytokine changes were induced by coculturing renal tubular cells with adipocytes and/or macrophages without direct contact, indicating that crosstalk between adipocytes/macrophages and renal tubular cells was mediated by soluble factors. The susceptibility to urolithiasis of patients with metabolic syndrome might be due to aggravated inflammation of renal tubular cells triggered by a paracrine mechanism involving these 3 cell types. Copyright © 2014 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Decontamination effectiveness of mixtures of citric acid, oxalic acid and EDTA

International Nuclear Information System (INIS)

Speranzini, R.A.

1990-01-01

An experimental study of the decontamination effectiveness of citric acid, oxalic acid and EDTA mixtures was conducted to assess whether oxalic acid could be removed from decontamination solutions to minimize corrosion. In loop experiments, radioactive specimens from two boiling water reactors and one pressurized water reactor were suspended in solutions of single acids or in mixtures of reagents at total reagent concentrations of less than 0.1 wt% under conditions similar to those used to decontaminate reactor systems. Rate constants for dissolution of oxides and decontamination factors were measured. Based on the results, it was concluded that under certain conditions, oxalic acid was the most effective reagent for the dissolution of oxides. It was also found, however, that conditions under which effective dissolution occurred in solutions of oxalic acid and/or citric acid were difficult to define and control. EDTA was found to be an effective reagent for dissolution of oxides such that rates of dissolution in EDTA containing solutions at 117 degrees Celsius were comparable to rates in oxalic acid containing solutions. At 90 degrees Celsius, EDTA acted synergistically with oxalic acid such that the rate of dissolution of oxides in citric-acid/oxalic-acid/EDTA solutions was higher than in citric-acid/EDTA solutions. The rates of dissolution of oxides were significantly reduced when 60 mg/kg of ferric ion was added to the citric-acid/oxalic-acid, citric-acid/EDTA and citric-acid/oxalic-acid/EDTA solutions. It was concluded that effective decontaminations of BWR and PWR systems could be achieved with mixtures of citric acid and EDTA

Cassava Pulp Hydrolysis under Microwave Irradiation with Oxalic Acid Catalyst for Ethanol Production

Directory of Open Access Journals (Sweden)

Euis Hermiati

2014-07-01

Full Text Available Microwave irradiation is an alternative method of starch hydrolysis that offers a rapid process. The aim of this research was to improve microwave-assisted hydrolysis of cassava pulp by using oxalic acid as a catalyst. Suspension of cassava pulp in 0.5% oxalic acid (1 g/20 mL was subjected to microwave irradiation at 140-230 °C for 5 minutes, with 4 minutes of pre-heating. One gram of fractured activated carbon made of coconut shell was added into a number of suspensions that were subjected to the same conditions of microwave irradiation. The soluble fraction of the hydrolysates was analyzed for its total soluble solids, malto-oligomer distribution, glucose content, pH value, and formation of brown compounds. The effects of the combined severity parameter at a substrate concentration of 5-12.5% on the glucose yield were also evaluated. The highest glucose yield (78% of dry matter was obtained after hydrolysis at 180 °C without activated carbon addition. Heating above 180 °C reduced the glucose yield and increased the pH and the formation of brown compounds. The use of activated carbon in microwave-assisted acid hydrolysis of cassava pulp reduced the glucose yield, but suppressed the formation of brown compounds. The highest glucose yield (70-80% of dry matter was attained at a severity parameter of 1.3-1.5.

The metabolic and ecological interactions of oxalate-degrading bacteria in the Mammalian gut.

Science.gov (United States)

Miller, Aaron W; Dearing, Denise

2013-12-06

Oxalate-degrading bacteria comprise a functional group of microorganisms, commonly found in the gastrointestinal tract of mammals. Oxalate is a plant secondary compound (PSC) widely produced by all major taxa of plants and as a terminal metabolite by the mammalian liver. As a toxin, oxalate can have a significant impact on the health of mammals, including humans. Mammals do not have the enzymes required to metabolize oxalate and rely on their gut microbiota for this function. Thus, significant metabolic interactions between the mammalian host and a complex gut microbiota maintain the balance of oxalate in the body. Over a dozen species of gut bacteria are now known to degrade oxalate. This review focuses on the host-microbe and microbe-microbe interactions that regulate the degradation of oxalate by the gut microbiota. We discuss the pathways of oxalate throughout the body and the mammalian gut as a series of differentiated ecosystems that facilitate oxalate degradation. We also explore the mechanisms and functions of microbial oxalate degradation along with the implications for the ecological and evolutionary interactions within the microbiota and for mammalian hosts. Throughout, we consider questions that remain, as well as recent technological advances that can be employed to answer them.

X-ray fluorescence analysis of praseodymium oxide/oxalate for rare earth impurities

International Nuclear Information System (INIS)

Chandola, L.C.; Mohile, A.N.

1976-01-01

A method for the determination of lanthanum, cerium, neodymium and samarium oxides in praseodymium oxide is described. The sample in the oxalate form is mixed with boric acid binder in the weight ratio of 1:1 and pressed into a pellet. The pellet is irradiated by X-rays from a tungsten tube and fluorescent X-rays are dispersed by a LiF (200) crystal in a Philips semiautomatic X-ray fluorescence spectrometer. The intensity of the characteristic X-rays of the impurity elements is measured by a flow proportional counter at selected 20 angles. The minium determination limit is 0.01% for all impurities. (author)

Two-stage precipitation of neptunium (IV) oxalate

International Nuclear Information System (INIS)

Luerkens, D.W.

1983-07-01

Neptunium (IV) oxalate was precipitated using a two-stage precipitation system. A series of precipitation experiments was used to identify the significant process variables affecting precipitate characteristics. Process variables tested were input concentrations, solubility conditions in the first stage precipitator, precipitation temperatures, and residence time in the first stage precipitator. A procedure has been demonstrated that produces neptunium (IV) oxalate particles that filter well and readily calcine to the oxide

Preparation, characterization and catalytic effects of copper oxalate nanocrystals

International Nuclear Information System (INIS)

Singh, Gurdip; Kapoor, Inder Pal Singh; Dubey, Reena; Srivastava, Pratibha

2012-01-01

Graphical abstract: Prepared copper oxalate nanocrystals were characterized by FE-SEM and bright field TEM micrographs. Its catalytic activity was evaluated on the thermal decomposition of ammonium perchlorate using TG and TG-DSC techniques. Highlights: ► Preparation of nanocrystals (∼9.0 nm) of copper oxalate using Cu(NO 3 ) 2 ·2H 2 O, oxalic acid and acetone under thermal conditions. ► Method is simple and novel. ► Characterization using XRD, SEM, TEM, HRTEM and ED pattern. ► Catalytic activity of copper oxalate nanocrystals on AP thermal decomposition using thermal techniques (TG, TG-DSC and ignition delay). ► Kinetics of thermal decomposition of AP + CONs using isoconversional and model fitting kinetic approaches. - Abstract: Recent work has described the preparation and characterization of copper oxalate nanocrystals (CONs). It was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and electron diffraction pattern (ED). The catalytic activity of CONs on the thermal decomposition of ammonium perchlorate (AP) and composite solid propellants (CSPs) has been done by thermogravimetry (TG), differential scanning calorimetry (DSC) and ignition delay measurements. Burning rate of CSPs was also found to be enhanced in presence of copper oxalate nanocrystals. Kinetics of thermal decomposition of AP with and without CONs has also been investigated. The model free (isoconversional) and model-fitting kinetic approaches have been applied to data for isothermal TG decomposition.

Inorganic salts interact with oxalic acid in submicron particles to form material with low hygroscopicity and volatility

Science.gov (United States)

Drozd, G.; Woo, J.; Häkkinen, S. A. K.; Nenes, A.; McNeill, V. F.

2014-05-01

Volatility and hygroscopicity are two key properties of organic aerosol components, and both are strongly related to chemical identity. While the hygroscopicities of pure salts, di-carboxylic acids (DCA), and DCA salts are known, the hygroscopicity of internal mixtures of these components, as they are typically found in the atmosphere, has not been fully characterized. Here we show that inorganic-organic component interactions typically not considered in atmospheric models can lead to very strongly bound metal-organic complexes and greatly affect aerosol volatility and hygroscopicity; in particular, the bi-dentate binding of DCA to soluble inorganic ions. We have studied the volatility of pure, dry organic salt particles and the hygroscopicity of internal mixtures of oxalic acid (OxA, the dominant DCA in the atmosphere) and a number of salts, both mono- and di-valent. The formation of very low volatility organic salts was confirmed, with minimal evaporation of oxalate salt particles below 75 °C. Dramatic increases in the cloud condensation nuclei (CCN) activation diameter for particles with di-valent salts (e.g., CaCl2) and relatively small particle volume fractions of OxA indicate that standard volume additivity rules for hygroscopicity do not apply. Thus small organic compounds with high O : C ratios are capable of forming low-volatility and very low hygroscopicity particles. Given current knowledge of the formation mechanisms of OxA and M-Ox salts, surface enrichment of insoluble M-Ox salts is expected. The resulting formation of an insoluble coating of metal-oxalate salts can explain low-particle hygroscopicities. The formation of particles with a hard coating could offer an alternative explanation for observations of glass-like particles without the need for a phase transition.

Features of atopic dermatitis in children with oxalic acid dysmetabolism

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T.V. Stoieva

2018-03-01

Full Text Available The article presents the features of atopic dermatitis in children with concomitant metabolic disturbances of oxalic acid. The influence of metabolic shifts was evaluated by clinical presentation, morphofunctional parameters of the skin and the features of oxalic acid metabolites excretion. In this study, a high incidence of dysmetabolic changes was identified, their significance was determined by the involvement of different systems for oxalic acid products excretion. The increased concentration of oxalate in the urine and in the exhaled air condensate had irritant effect and is associated with the hereditary metabolic disorders, early manifestation of atopy symptoms and the intensity of skin itching, with moderate increase of immunoglobulin E level.

Novel Inorganic Coordination Polymers Based on Cadmium Oxalates

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Prasad, P. A.; Neeraj, S.; Vaidhyanathan, R.; Natarajan, Srinivasan

2002-06-01

Three new cadmium oxalate coordination polymers, I-III, with extended layered structures have been synthesized in the presence of imidazole. While I was prepared by the reaction between imidazolium oxalate and Cd, II and III were synthesized from their constituents using hydrothermal methods. [Cd(C2O4)(C3N2H4)]∞ (I): monoclinic, space group P21/c (no. 14), a=8.7093(1) Å, b=9.9477(3) Å, c=8.4352 Å, β=93.796(1)°, Z=4; [Cd(C2O4)2(C3N2H4)3(H2O)]∞ (II): monoclinic, space group P21/c (no. 14), a=7.8614(2) Å, b=14.9332(3) Å, c=15.9153(4) Å β=94.587(1)°, Z=4; [Cd(C2O4)2(C3N2H4)3(H2O)]∞ (III): monoclinic, space group P21/c (no. 14), a=11.844(2) Å, b=9.066(1) Å, c=18.583(2) Å, β=103.84(2)°, Z=4. While the structure of I is made from CdO5N distorted octahedra linked with oxalate, II and III are built-up from CdO6N, CdO5N2 distorted pentagonal bi-pyramids connected to oxalate units. The framework formulas of II and III are identical and their structures closely related. In all the cases, the networking between the Cd-O/N polyhedra and oxalates give rise to layered architectures with the amine molecules pointing in a direction perpendicular to the layers (in the inter-lamellar region). The difference in the linkages between the oxalates and the Cd atoms in I-III, produces unusual Cd-O-Cd one-dimensional chains, which have been observed for the first time.

Total, Soluble and Insoluble Oxalate Contents of Ripe Green and Golden Kiwifruit.

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Nguyễn, Hà Vũ Hồng; Savage, Geoffrey P

2013-03-05

Three bulk samples of two different cultivars of kiwifruit, green ( Actinidia deliciosa L . ) and golden ( Actinidia chinensis L . ) were bought ripe, ready to eat from a local market. The aim of the study was to determine the oxalate composition of each of the three fractions of kiwifruit, namely skin, pulp and seeds. The pulp consisted of 90.4% of the edible portion of the two cultivars while the skin and seeds made up a mean of 8.0% and 1.6% respectively. Total oxalate was extracted with 2.0 M HCL at 21 °C for 15 min and soluble oxalates extracted at 21 °C in water for 15 min from each fraction. The total and soluble oxalate compositions of each fraction were determined using ion exchange HPLC chromatography. The pulp of golden kiwifruit contained lower amounts of total oxalates (15.7 vs. 19.3 mg/100 g FW) and higher amounts of soluble oxalates (8.5 vs. 7.6 mg/100 g FW) when compared to the green cultivar. The skin of the green cultivar contained lower levels of insoluble oxalates (36.9 vs. 43.6 mg/100 g FW), while the seeds of the green cultivar contained higher levels of insoluble oxalates 106.7 vs. 84.7 mg/100 g FW.

Urinary oxalate excretion, as determined by isotope dilution and indirect colorimetry

International Nuclear Information System (INIS)

Prenen, J.A.C.; Boer, P.; Leersum, L. van; Oldenburg, S.J.; Endeman, H.J.

1983-01-01

A simple and reliable method for the determination of urinary oxalate excretion is described. Urinary oxalate is precipitated with calcium chloride, and the oxalate content of the precipitate is measured by an indirect colorimetric method developed by Neas and Guyon in 1972. For single urine samples, a correction is made for the incompleteness of the precipitation of calcium oxalate by isotope dilution. The range of normal values (5% limits) determined in 52 normal subjects was 0.121-0.325 mmol.24 h - 1 .m - 2 for a 1-day collection period and 0.145-0.301 mmol. 24 h - 1 .m - 2 for a 3-day collection period. The within-assay CV of a control urine with a low oxalate concentration was 9% (n=7) and the between-assay CV for the same control urine was 12% (n=6). When the values obtained for oxalate excretion were normalized to body surface area, there was no significant difference between males and females; the main source of variation was the intra-individual variation. (Auth.)

Availability of calcium from chemically pure potassium oxalate to the buffalo (Bubalus bubalis)

International Nuclear Information System (INIS)

Singh, Sudarshan; Sareen, V.K.; Marwah, S.R.; Sharma, K.C.; Bhatia, I.S.

1978-01-01

Three experiments were conducted to determine the true dige'stibility of calcium in the buffalo calves fed chemically pure potassium oxalate. In each experiments 6 calves were divided into two groups, viz. control and oxalate-fed. The control group was given basal ration consisting of wheat straw, mustard-cake and maize grains. The oxalate-fed group was fed the basal ration supplemented with 60, 100 and 140 g potassium oxalate per day in experiments 1,2, and 3 respectively. The percent true digestibility of calcium was 51.7 and 52.5 in experiment 1, 60.5 and 44.1 in experiment 2, and 59.3 and 44.1 in experiment 3 in the control and oxalate-fed groups respectively. In all the experiments the oxalate was completely broken down in the rumen. The volume of water intake and urine excretion was more in the oxalate-fed groups. The daily alkali output in the urine in terms of N-acid was 0.7 and 1.3 in experiment 1, 1.5 and 2.5 in experiment 2, and 2.1 and 3.8 in experiment 3 in control and oxalate-fed groups respectively. The daily bicarbonate concentration in the urine (in g) was 26.5 and 53.4 in experiment 1, 83.2 and 146.2 in experiment 2, and 132.6 and 222.8 in experiment 3 in control and oxalate-fed groups respectively. Likewise the excretion of oxalate in the urine was more in oxalate-fed groups. On the basis of the results obtained, the reason for the somewhat low true digestibility of calcium in the calves consuming more than 60 g of potassium oxalate/day are discussed. Isotope-dilution technique using 45 CaCl 2 was employed in the study. (auth.)

Direct observation of two-step crystallization in nanoparticle superlattice formation

Energy Technology Data Exchange (ETDEWEB)

Park, Jungwon; Zheng, Haimei; Lee, Won Chul; Geissler, Phillip L.; Rabani, Eran; Alivisatos, A. Paul

2011-10-06

Direct imaging of nanoparticle solutions by liquid phase transmission electron microscopy has enabled unique in-situ studies of nanoparticle motion and growth. In the present work, we report on real-time formation of two-dimensional nanoparticle arrays in the very low diffusive limit, where nanoparticles are mainly driven by capillary forces and solvent fluctuations. We find that superlattice formation appears to be segregated into multiple regimes. Initially, the solvent front drags the nanoparticles, condensing them into an amorphous agglomerate. Subsequently, the nanoparticle crystallization into an array is driven by local fluctuations. Following the crystallization event, superlattice growth can also occur via the addition of individual nanoparticles drawn from outlying regions by different solvent fronts. The dragging mechanism is consistent with simulations based on a coarse-grained lattice gas model at the same limit.

Nephroprotective effect of Corn Silk extract on oxalic acid-induced nephrocalcinosis in rabbit model

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Faruk Hassan Al-Jawad

2012-04-01

Full Text Available ABSTRACT Background : Nephrocalcinosis is a state of deposition of calcium phosphate or oxalate in the renal parenchyma. It may occur in patients with renal tubular acidosis, vitamin D intoxication, and hyperparathyroidism. Corn silk was used in traditional Chinese medicine to relieve renal pains. Aim: To evaluate the effect of Corn silk aqueous extract in reducing calcium deposits from renal parenchyma in oxalic acid-induced nephrocalcinosis model. Materials and methods: Fourteen healthy rabbits were allocated to two groups. Two hours before induction of nephrocalcinosis, one group received water and the other received aqueous extract of corn silk and continued feeding for ten days. Blood samples were collected for biochemical analysis before induction and in the fifth and tenth post-induction day. Urine samples were taken to estimate urinary ca+2 levels and crystals. The histopathological examination was carried to check for crystal deposits in renal tissues. Results: Corn silk aqueous extract produced a significant reduction of blood urea nitrogen(5.2+/-0.08 vs 7.3+/-0.2 mmol/l, serum creatinine (85.9+/-0.2 vs 97.3+/-0.5 mmol/l and serum Na+ levels (137+/-0.2 vs 142.16+/-0.7 mmol/l with non-significant reduction in serum K+ (4.0+/-0.02 vs 4.2+/-0.05. There is a significant reduction in calcium deposition in renal parenchyma in comparison to the control group after ten days of treatment. Conclusion: Corn silk had a significant diuretic effect that accelerates the excretion of urinary calcium. [J Intercult Ethnopharmacol 2012; 1(2.000: 75-78

Heterogeneous nucleation of calcium oxalate on native oxide surfaces

International Nuclear Information System (INIS)

Song, L.; Pattillo, M.J.; Graff, G.L.; Campbell, A.A.; Bunker, B.C.

1994-04-01

The aqueous deposition of calcium oxalate onto colloidal oxides has been studied as a model system for understanding heterogeneous nucleation processes of importance in biomimetic synthesis of ceramic thin films. Calcium oxalate nucleation has been monitored by measuring induction times for nucleation using Constant Composition techniques and by measuring nucleation densities on extended oxide surfaces using an atomic force microscope. Results show that the dependence of calcium oxalate nucleation on solution supersaturation fits the functional form predicted by classical nucleation theories. Anionic surfaces appear to promote nucleation better than cationic surfaces, lowering the effective energy barrier to heterogeneous nucleation

Total, Soluble and Insoluble Oxalate Contents of Ripe Green and Golden Kiwifruit

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Hà Vũ Hồng Nguyễn

2013-03-01

Full Text Available Three bulk samples of two different cultivars of kiwifruit, green (Actinidia deliciosa L. and golden (Actinidia chinensis L. were bought ripe, ready to eat from a local market. The aim of the study was to determine the oxalate composition of each of the three fractions of kiwifruit, namely skin, pulp and seeds. The pulp consisted of 90.4% of the edible portion of the two cultivars while the skin and seeds made up a mean of 8.0% and 1.6% respectively. Total oxalate was extracted with 2.0 M HCL at 21 °C for 15 min and soluble oxalates extracted at 21 °C in water for 15 min from each fraction. The total and soluble oxalate compositions of each fraction were determined using ion exchange HPLC chromatography. The pulp of golden kiwifruit contained lower amounts of total oxalates (15.7 vs. 19.3 mg/100 g FW and higher amounts of soluble oxalates (8.5 vs. 7.6 mg/100 g FW when compared to the green cultivar. The skin of the green cultivar contained lower levels of insoluble oxalates (36.9 vs. 43.6 mg/100 g FW, while the seeds of the green cultivar contained higher levels of insoluble oxalates 106.7 vs. 84.7 mg/100 g FW.

Trichoderma koningii as a biomineralizing fungous agent of calcium oxalate crystals in typical Argiudolls of the Los Padres Lake natural reserve (Buenos Aires, Argentina).

Science.gov (United States)

Oyarbide, F; Osterrieth, M L; Cabello, M

2001-01-01

The aim of the present study, performed on typical Argiudolls in a natural reserve with little or no anthropic impact, was to characterize the fungous biomineralizing process of calcium oxalate crystals in organic horizons of the soil. The chosen sites possessed different plant cover, identified as acacia woods and grassy meadows with particular micro environmental conditions that have differing effects in the process of biomineralization. The contribution of the plant material in the soil is a key factor since 1) it generates the particular composition of the organic horizons, 2) it determines the nature of decomposing organisms, and 3) it affects the presence, composition and development of biominerals. According to the results obtained, the acacia woods prove to be a site comparatively more favorable to the fungous biomineralizing process. This makes itself manifest in the greater abundance and development of crystals in the organic horizons of the soil, resulting in whewellite (CaC2O4.H2O) and weddellite (CaC2O4.(2+x) H2O) regarding biomineral species developed, the latter being the major component. The observation of both species of biominerals is noteworthy since it represents the first cited in the country. The isolated fungous organisms were Trichoderma koningii, and Absidia corymbifera. T. koningii was identified as the most active biomineralizing organism thus constituting the first reference to indicate this species as a biomineral producing agent.

Effects of Juice Processing on Oxalate Contents in Carambola Juice Products.

Science.gov (United States)

Huynh, Nha K; Nguyen, Ha V H

2017-09-01

Effects of processing methods including pressing, enzyme-assisted extraction, lactic acid fermentation by Lactobacillus acidophilus, and alcohol fermentation by Saccharomyces cerevisiae on total and soluble oxalate contents of carambola juices were studied. In comparison with pressing, the use of enzyme increased juice yields (15.89-17.29%), but resulted in higher total oxalate (1.60-1.73 times) and soluble oxalate contents (1.16-1.49 times). In addition, extension of enzyme incubation periods led to an increase in soluble oxalate contents in the products (p carambola juices. These results suggested that carambola juice products should only be consumed moderately, and that alcohol fermentation could be a potential method to reduce oxalate contents in foods in order to prevent the risks of forming kidney stones.

Reaction of Hydrazine Hydrate with Oxalic Acid: Synthesis and ...

African Journals Online (AJOL)

NICO

2013-11-28

Nov 28, 2013 ... The title compound is a molecular salt containing two discrete hydrazinium cations and an oxalate anion. The oxalate ... RESEARCH ARTICLE ... Scheme and reaction showing the simple experimental procedure for the preparation of .... 7 A.I. Vogel, A Text Book of Quantitative Inorganic Analysis, 4th edn.,.

Studies on the decomposition of oxalic acid by nitric acid in presence of catalysts

International Nuclear Information System (INIS)

Noronha, D.M.; Pius, I.C.; Chaudhury, S.

2015-01-01

Impure Plutonium oxalate generated from the recovery of plutonium from waste solutions may require further purification via anion exchange. Conventionally, plutonium oxalate is converted to oxide in a furnace and the oxide is dissolved in Conc. HNO 3 containing HF and purified by anion exchange route. Studies initiated on the decomposition of oxalic acid with Conc. HNO 3 to facilitate direct dissolution of plutonium oxalate and quantitative destruction of oxalate are discussed in this paper. (author)

Extraction and estimation of the quantity of calcium oxalate crystals in the foliage of conifer and hardwood trees

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Rakesh Minocha; Bradley Chamberlain; Stephanie Long; Swathi A. Turlapati; Gloria. Quigley

2015-01-01

The main goal of this study was to develop a method for the extraction and indirect estimation of the quantity of calcium oxalate (CaOx) in the foliage of trees. Foliar tissue was collected from a single tree of each species (five conifers and five hardwoods) for comparison of extractions in different solvents using 10 replicates per species from the same pool of...

Optimization of precipitation conditions of thorium oxalate precipitate

International Nuclear Information System (INIS)

Pazukhin, Eh.M.; Smirnova, E.A.; Krivokhatskij, A.S.; Pazukhina, Yu.L.; Kiselev, P.P.

1986-01-01

Thorium precipitation in the form of difficultly soluble oxalate has been investigated. The equation binding the concentration of metal with the nitric acid in the initial solution and quantity of a precipitator necessary for minimization of desired product losses is derived. The graphical solution of this equation for a case, when the oxalic acid with 0.78 mol/l concentration is the precipitator, is presented

Nanodefect formation in LiF crystals under gamma irradiation

International Nuclear Information System (INIS)

Mussaeva, M.A.; Ibragimova, Eh.M.; Kalanov, M.U.; Muminov, M.I.

2006-01-01

One studied the spectra of absorption and of photoluminescence, microhardness and performed X-ray structure analysis of gamma-irradiated LiF crystals in a shutdown reactor and in 60 Co source when gamma-radiation dose rate was equal to 7.65 Gy/s. In addition to formation of point and combined radiation defects one detected the presence of the gamma-irradiation induced 28 nm size nanoparticles of LiOH phase in Li sublattice. Formation of defects is shown to occur more efficiently in a shutdown reactor in contrast to 60 Co source [ru

Urinary calculi in hypercalcemic states.

Science.gov (United States)

Thomas, W C

1990-12-01

In this brief review of various hypercalcemic disorders and the likelihood of renal calculus formation, it is clearly evident that renal calculi occur much more often in hyperparathyroidism than in the other hypercalcemic states. Dystrophic calcification and nephrocalcinosis are common to all of the hypercalcemic disorders, including hyperparathyroidism, when the hypercalcemia is marked and the limit of solubility of calcium and phosphate in serum is approached. Interestingly, in sarcoidosis there are calcium oxalate crystals in variously distributed sarcoid granuloma, and the renal calculi are composed of calcium oxalate. By contrast, in hyperparathyroidism, the calculi composed of calcium phosphate predominate. This indicates a subtle and as yet undefined alteration in oxalate metabolism in sarcoidosis. An increase in urine pH occurs in hyperparathyroidism, and this enhances formation of crystalline calcium phosphate. However, the striking disparity between the frequency of calculus formation in hyperparathyroidism and that in other hypercalcemic disorders, several of which may be of relatively long duration, suggests that there indeed may be increased promoters of crystal formation in the urine of hyperparathyroid patients.

Crystallization and preliminary X-ray analysis of formate oxidase, an enzyme of the glucose–methanol–choline oxidoreductase family

International Nuclear Information System (INIS)

Maeda, Yoshifumi; Doubayashi, Daiju; Ootake, Takumi; Oki, Masaya; Mikami, Bunzo; Uchida, Hiroyuki

2010-01-01

Formate oxidase from A. oryzae RIB40 was crystallized and diffraction data were collected to a resolution of 2.4 Å. Formate oxidase (FOD), which catalyzes the oxidation of formate to yield carbon dioxide and hydrogen peroxide, belongs to the glucose–methanol–choline oxidoreductase (GMCO) family. FOD from Aspergillus oryzae RIB40, which has a modified FAD as a cofactor, was crystallized at 293 K by the hanging-drop vapour-diffusion method. The crystal was orthorhombic and belonged to space group C222 1 . Diffraction data were collected from a single crystal to 2.4 Å resolution

Membrane inlet mass spectrometry reveals that Ceriporiopsis subvermispora bicupin oxalate oxidase is inhibited by nitric oxide.

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Moomaw, Ellen W; Uberto, Richard; Tu, Chingkuang

2014-07-18

Membrane inlet mass spectrometry (MIMS) uses a semipermeable membrane as an inlet to a mass spectrometer for the measurement of the concentration of small uncharged molecules in solution. We report the use of MIMS to characterize the catalytic properties of oxalate oxidase (E.C. 1.2.3.4) from Ceriporiopsis subvermispora (CsOxOx). Oxalate oxidase is a manganese dependent enzyme that catalyzes the oxygen-dependent oxidation of oxalate to carbon dioxide in a reaction that is coupled with the formation of hydrogen peroxide. CsOxOx is the first bicupin enzyme identified that catalyzes this reaction. The MIMS method of measuring OxOx activity involves continuous, real-time direct detection of oxygen consumption and carbon dioxide production from the ion currents of their respective mass peaks. (13)C2-oxalate was used to allow for accurate detection of (13)CO2 (m/z 45) despite the presence of adventitious (12)CO2. Steady-state kinetic constants determined by MIMS are comparable to those obtained by a continuous spectrophotometric assay in which H2O2 production is coupled to the horseradish peroxidase catalyzed oxidation of 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid). Furthermore, we used MIMS to determine that NO inhibits the activity of the CsOxOx with a KI of 0.58±0.06 μM. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Preparation of High-purity Indium Oxalate Salt from Indium Scrap by Organic Acids

International Nuclear Information System (INIS)

Koo, Su-Jin; Ju, Chang-Sik

2013-01-01

Effect of organic acid on the preparation of indium-oxalate salt from indium scraps generated from ITO glass manufacturing process was studied. Effects of parameters, such as type and concentration of organic acids, pH of reactant, temperature, reaction time on indium-oxalate salt preparation were examined. The impurity removal efficiency was similar for both oxalic acid and citric acid, but citric acid did not make organic acid salt with indium. The optimum conditions were 1.5 M oxalic acid, pH 7, 80 .deg. C, and 6 hours. On the other hand, the recoveries increased with pH, but the purity decreased. The indium-oxalate salt purity prepared by two cycles was 99.995% (4N5). The indium-oxalate salt could be converted to indium oxide and indium metal by substitution reaction and calcination

Wu-Ling-San formula prophylaxis against recurrent calcium oxalate ...

African Journals Online (AJOL)

Wu-Ling-San (WLS) formula has been proved to prevent calcium oxalate nephrolithiasis both in vitro and in vivo. This is the first prospective, randomized and placebo-controlled clinical trial of WLS in calcium oxalate nephrolithiasis prevention. All patients who enrolled were asked to drink enough fluid to urinate at least 2 L ...

Synthesis of unsymmetrical dimethylhydrazine oxalate from rejected liquid rocket propellant

Science.gov (United States)

Mu, Xiaogang; Yang, Jingjing; Zhang, Youzhi

2018-02-01

The rejected liquid propellant unsymmetrical dimethylhydrazine (UDMH) was converted to UDMH oxalate, which has commercial value. The UDMH oxalate structure and stability were investigated by the Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and ultraviolet-visible spectrophotometric analysis. The results indicate that UDMH oxalate has good thermal and aqueous solution stability, a melting point of 144 °C, an initial decomposition temperature of 180 °C, and a peak wavelength of UV in aqueous solution at λ = 204 nm. This disposal method of rejected UDMH is highly efficient and environmentally safe.

Oxalate Encapsulation in Aqueous Medium by Tripodal Urea ...

Indian Academy of Sciences (India)

1H-NMR titration studies: All 1H-NMR titration experiments for L1 and L2 were conducted on a Bruker 300 MHz spectrometer at 298 K respectively. Potassium oxalate dihydrate (K2C2O4.2H2O) was used to prepare the stock solution of anion in DMSO-d6:D2O (1:1.1) solvent system. Lower solubility of potassium oxalate in ...

Reductive and oxidative degradation of iopamidol, iodinated X-ray contrast media, by Fe(III)-oxalate under UV and visible light treatment.

Science.gov (United States)

Zhao, Cen; Arroyo-Mora, Luis E; DeCaprio, Anthony P; Sharma, Virender K; Dionysiou, Dionysios D; O'Shea, Kevin E

2014-12-15

Iopamidol, widely employed as iodinated X-ray contrast media (ICM), is readily degraded in a Fe(III)-oxalate photochemical system under UV (350 nm) and visible light (450 nm) irradiation. The degradation is nicely modeled by pseudo first order kinetics. The rates of hydroxyl radical (OH) production for Fe(III)-oxalate/H2O2/UV (350 nm) and Fe(III)-oxalate/H2O2/visible (450 nm) systems were 1.19 ± 0.12 and 0.30 ± 0.01 μM/min, respectively. The steady-state concentration of hydroxyl radical (OH) for the Fe(III)-oxalate/H2O2/UV (350 nm) conditions was 10.88 ± 1.13 × 10(-14) M and 2.7 ± 0.1 × 10(-14) M for the Fe(III)-oxalate/H2O2/visible (450 nm). The rate of superoxide anion radical (O2(-)) production under Fe(III)-oxalate/H2O2/UV (350 nm) was 0.19 ± 0.02 μM/min with a steady-state concentration of 5.43 ± 0.473 × 10(-10) M. Detailed product studies using liquid chromatography coupled to Q-TOF/MS demonstrate both reduction (multiple dehalogenations) and oxidation (aromatic ring and side chains) contribute to the degradation pathways. The reduction processes appear to be initiated by the carbon dioxide anion radical (CO2(-)) while oxidation processes are consistent with OH initiated reaction pathways. Unlike most advanced oxidation processes the Fe(III)-oxalate/H2O2/photochemical system can initiate to both reductive and oxidative degradation processes. The observed reductive dehalogenation is an attractive remediation strategy for halogenated organic compounds as the process can dramatically reduce the formation of the problematic disinfection by-products often associated with oxidative treatment processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

NDA technique for the assay of wet plutonium oxalate

International Nuclear Information System (INIS)

Marshall, R.S.; Canada, T.R.

1980-01-01

A method has been developed to quantitatively measure batches of wet plutonium oxalate. The method is based on a count of coincidence neutrons to which a correction is applied for the effects of neutron moderation by water. A therma-neutron coincidence counter (TNC) with two concentric rings of 3 He detectors provides the signal needed for the water correction. The signal is the ratio of neutron counts between the detector rings that changes with the percent of water in plutonium oxalate. To evaluate the measurement technique, 26 batches of plutonium oxalate were measured in an in-line TNC. The evaluation showed the measurements to be essentially unbiased and precise to 2.2%

Interaction Studies of Dilute Aqueous Oxalic Acid

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Kiran Kandpal

2007-01-01

Full Text Available Molecular conductance λm, relative viscosity and density of oxalicacid at different concentration in dilute aqueous solution were measured at 293 K.The conductance data were used to calculate the value association constant.Viscosity and density data were used to calculate the A and B coefficient ofJone-Dole equation and apparent molar volume respectively. The viscosityresults were utilized for the applicability of Modified Jone-Dole equation andStaurdinger equations. Mono oxalate anion acts, as structure maker and thesolute-solvent interaction were present in the dilute aqueous oxalic acid.

Massive Formation of Equiaxed Crystals by Avalanches of Mushy Zone Segments

Science.gov (United States)

Ludwig, A.; Stefan-Kharicha, M.; Kharicha, A.; Wu, M.

2017-06-01

It is well known that the growth and motion of equiaxed crystals govern important microstructural features, especially in larger castings such as heavy ingots. To determine the origin of the equiaxed crystals, heterogeneous nucleation, and/or fragmentation of dendrite arms from columnar regions are often discussed. In the present study, we demonstrate that under certain conditions relatively large areas of mushy regions slide downward and form spectacular crystal avalanches. These avalanches crumble into thousands of dendritic fragments, whereby the larger fragments immediately sediment and the smaller proceed to behave as equiaxed crystals. Traces of such crystal avalanches can be seen by conspicuous equiaxed layers in the lower part of the casting. From the arguments in the discussion, it is believed that such a phenomenon may occur in alloys which reveal an upward solutal buoyancy in the interdendritic mush. This would include certain steels and other alloys such as Cu-Al, Pb-Sn, or Ni-Al-alloys. Moreover, the occurrence of crystal avalanches contribute to the formation of V-segregations.

Correlation between the development of calcium oxalate stones and polymorphisms in the fibronectin gene in the Uighur population of the Xinjiang region of China.

Science.gov (United States)

Murat, M; Aekeper, A; Yuan, L Y; Alim, T; Du, G J; Abdusamat, A; Wu, G W; Aniwer, Y

2015-10-29

Here, we have investigated the correlation between calcium oxalate stone formation and Fn gene polymorphisms in urinary calculi patients among the Uighur population (Xinjiang region). In this case control study, genomic DNA extracted from the peripheral blood of 129 patients with calcium oxalate stones (patient group) and 94 normal people (control group) was used to genotype polymorphisms in the rs6725958, rs10202709, and rs35343655 sites of the Fn gene by polymerase chain reaction-restriction fragment length polymorphism. Subsequently, the association between different genotypes and susceptibility to calcium oxalate stone formation was compared among the patient and control groups. Single nucleotide polymorphisms (SNPs) were detected in the rs6725958, rs10202709, and rs35343655 sites of the Fn gene among the patient and control groups. The genotype distributions of the three loci complied with the Hardy-Weinberg equilibrium. The results of allele frequencies of the patient/control group for polymorphisms in the rs6725958 site of the Fn gene were C = 179 (69.92%)/119 (63.30%) and A = 77 (30.08%)/69 (36.70%), in the rs10202709 site were C = 245 (95.70%)/176 (93.63%) and T = 11 (4.30%)/12 (6.38%), and in the rs35343655 site of the Fn gene were A = 139 (54.30%)/87 (46.28%) and G = 117 (45.70%)/101 (53.72%). We observed no significant differences between the three SNPs and development of calcium oxalate stones. Polymorphisms in rs6725958, rs10202709, and rs35343655 of the Fn gene had no obvious effect on the susceptibility to the development of calcium oxalate stones in the Uighur population, residing in the Xinjiang region of China.

Characterization of oxalate-based 237NpO2 powder

International Nuclear Information System (INIS)

Rankin, D.T.; Burney, G.A.; Smith, P.K.; Sisson, R.D.

1976-01-01

238 Pu, a radioisotope heat source, is produced by irradiating reactor targets containing 237 NpO 2 . The neptunium oxide is obtained by precipitating and calcining 237 Np(IV) oxalate. The effects of oxalate precipitation parameters on particle morphology and size distribution of 237 NpO 2 powder were established to provide process controls for fabricating reactor targets

Hydrothermal synthesis and crystal structures of new uranyl oxalate hydroxides: α- and β-[(UO2)2(C2O4)(OH)2(H2O)2] and [(UO2)2(C2O4)(OH)2(H2O)2].H2O

International Nuclear Information System (INIS)

Duvieubourg, Laurence; Nowogrocki, Guy; Abraham, Francis; Grandjean, Stephane

2005-01-01

Two modifications of the new uranyl oxalate hydroxide dihydrate [UO 2 ) 2 (C 2 O 4 )(OH) 2 (H 2 O) 2 ] (1 and 2) and one form of the new uranyl oxalate hydroxide trihydrate [(UO 2 ) 2 (C 2 O 4 )(OH) 2 (H 2 O) 2 ].H 2 O (3) were synthesized by hydrothermal methods and their structures determined from single-crystal X-ray diffraction data. The crystal structures were refined by full-matrix least-squares methods to agreement indices R(wR)=0.0372(0.0842) and 0.0267(0.0671) calculated for 1096 and 1167 unique observed reflections (I>2σ(I)), for α (1) and β (2) forms, respectively and to R(wR)=0.0301(0.0737) calculated for 2471 unique observed reflections (I>2σ(I)), for 3. The α-form of the dihydrate is triclinic, space group P1-bar , Z=1, a=6.097(2), b=5.548(2), c=7.806(3)A, α=89.353(5), β=94.387(5), γ=97.646(5) o , V=260.88(15)A 3 , β-form is monoclinic, space group C2/c, Z=4, a=12.180(3), b=8.223(2), c=10.777(3)A, β=95.817(4), V=1073.8(5)A 3 . The trihydrate is monoclinic, space group P2 1 /c, Z=4, a=5.5095(12), b=15.195(3), c=13.398(3)A, β=93.927(3), V=1119.0(4)A 3 . In the three structures, the coordination of uranium atom is a pentagonal bipyramid composed of dioxo UO 2 2+ cation perpendicular to five equatorial oxygen atoms belonging to one bidentate oxalate ion, one water molecule and two hydroxyl ions in trans configuration in 2 and in cis configuration in 1 and 3. The UO 7 polyhedra are linked through hydroxyl oxygen atoms to form different structural building units, dimers [U 2 O 10 ] obtained by edge-sharing in 1, chains [UO 6 ] ∼ and tetramers [U 4 O 26 ] built by corner-sharing in 2 and 3, respectively. These units are further connected by oxalate entities that act as bis-bidentate to form one-dimensional chains in 1 and bi-dimensional network in 2 and 3. These chains or layers are connected in frameworks by hydrogen-bond arrays

Formation of oriented nitrides by N+ ion implantation in iron single crystals

International Nuclear Information System (INIS)

Costa, A.R.G.; Silva, R.C. da; Ferreira, L.P.; Carvalho, M.D.; Silva, C.; Franco, N.; Godinho, M.

2014-01-01

Iron single crystals were implanted with nitrogen at room temperature, with a fluence of 5×10 17 cm −2 and 50 keV energy, to produce iron nitride phases and characterize the influence of the crystal orientation. The stability and evolution of the nitride phases and diffusion of implanted nitrogen were studied as a function of successive annealing treatments at 250 °C in vacuum. The composition, structure and magnetic properties were characterized using RBS/channeling, X-Ray Diffraction, Magnetic Force Microscopy, Magneto-optical Kerr Effect and Conversion Electron Mössbauer Spectroscopy. In the as-implanted state the formation of Fe 2 N phase was clearly identified in all single crystals. This phase is not stable at 250 °C and annealing at this temperature promotes the formation of ε-Fe 3 N, or γ′-Fe 4 N, depending on the orientation of the substrate. - Highlights: • Oriented magnetic iron nitrides were obtained by nitrogen implantation into iron single crystals. • The stable magnetic nitride phase at 250 °C depends on the orientation of the host single crystal, being γ'-Fe 4 N or ε-Fe 3 N. • The easy magnetization axis was found to lay in the (100) plane for cubic γ'-Fe 4 N and out of (100) plane for hexagonal ε-Fe 3 N

General principles for the formation of dust self-organizing structures. Dust collective attraction and plasma crystal formation

International Nuclear Information System (INIS)

Tsytovich, V.N.

2005-01-01

It is demonstrated that a homogeneous dusty plasma is universally unstable to form structures. The effect of collective grain attraction is a basic phenomenon for the proposed new paradigm (general principles) for the plasma crystal formation

Modulation of Calcium Oxalate Crystallization by Proteins and Small Molecules Investigated by In Situ Atomic Force Microscopy

Science.gov (United States)

Qiu, R.; Orme, C.; Cody, A. M.; Wierzbicki, A.; Hoyer, J.; Nancollas, G.; de Yoreo, J.

2002-12-01

Understanding the physical mechanisms by which biological inhibitors control nucleation and growth of inorganic crystals is a major focus of biomineral research. Calcium oxalate monohydrate (COM), which plays a functional role in plant physiology, is also a source of pathogenesis in humans where it causes kidney stone disease. Although a great deal of research has been carried out on the modulation COM by proteins and small molecules, the basic mechanism has not yet been understood. However, because the proteins that play a role in COM growth have been identified and sequenced, COM provides an excellent model system for research into biomineral growth. In this study, in situ atomic force microscopy (AFM) was used to monitor the COM surface under controlled growth conditions both from pure solutions and those doped with citrate and osteopontin (OPN) in order to determine their effects on surface morphology and growth dynamics at the molecular level. As with other solution-grown crystals such as calcite, COM grows on complex dislocation hillocks. In pure solution, while growth on the (010) face is isotropic, hillocks on the (-101) face exhibit anisotropic step kinetics. Steps of [-10-1] and orientation are clearly delineated with the [-10-1] being the fast growing direction. When citrate is added to the solution, both growth rate and morphology are drastically changed on (-101) face, especially along the [-10-1] direction. This results in isotropic disc-shaped hillocks a shape that is then reflected in the macroscopic growth habit. In contrast, no large growth changes were observed on the (010) facet. At the same time, molecular modeling predicts an excellent fit of the citrate ion into the (-101) plane and a poor fit to the (010) face. Here we propose a model that reconciles the step-specific interactions implied by the AFM results with the face-specific predictions of the calculations. Finally, we present the results of doping with aspartic acid as well as OPN, an

Corrosion and impedance studies on magnesium alloy in oxalate solution

International Nuclear Information System (INIS)

Fekry, A.M.; Tammam, Riham H.

2011-01-01

Highlights: → Corrosion behavior of AZ91E alloy was investigated in 0.1 M Na 2 C 2 O 4 containing different additives as Br - , Cl - or Silicate. → The corrosion rate of 0.1 M oxalate solution containing silicate ion is lower than the blank (0.1 M Na 2 C 2 O 4 ). This was confirmed by scanning electron microscope (SEM) observations. → For the other added ions Br - or Cl - , the corrosion rate is higher than the blank. - Abstract: Corrosion behavior of AZ91E alloy was investigated in oxalate solution using potentiodynamic polarization and electrochemical impedance measurements (EIS). The effect of oxalate concentration was studied, where the corrosion rate increases with increasing oxalate concentration. The effect of added ions (Br - , Cl - or SiO 3 2- ) on the electrochemical behavior of magnesium alloy in 0.1 M Na 2 C 2 O 4 solution at 298 K, was investigated. It was found that the corrosion rate of 0.1 M oxalate solution containing silicate ion is lower than the blank (0.1 M Na 2 C 2 O 4 ). This was confirmed by scanning electron microscope (SEM) observations. However, for the other added ions Br - or Cl - , the corrosion rate is higher than the blank.

Oxalate complexation in dissolved carbide systems

International Nuclear Information System (INIS)

Choppin, G.R.; Bokelund, H.; Valkiers, S.

1983-01-01

It has been shown that the oxalic acid produced in the dissolution of mixed uranium, plutonium carbides in nitric acid can account for the problems of incomplete uranium and plutonium extraction on the Purex process. Moreover, it was demonstrated that other identified products such as benzene polycarboxylic acids are either too insoluble or insufficiently complexing to be of concern. The stability constants for oxalate complexing of UO 2 +2 and Pu +4 ions (as UO 2 (C 2 O 4 ), Pu(C 2 O 4 ) 2+ and Pu(C 2 O 4 ) 2 , respectively) were measured in nitrate solutions of 4.0 molar ionic strength (0-4 M HNO 3 ) by extraction of these species with TBP. (orig.)

Synthesis, structure and magnetic properties of a new iron phosphonate-oxalate with 3D framework: [Fe(O3PCH3)(C2O4)0.5(H2O)

International Nuclear Information System (INIS)

Zhang Yangyang; Qi Yue; Zhang Ying; Liu Ziyu; Zhao Yinfeng; Liu Zhongmin

2007-01-01

A new iron phosphonate-oxalate [Fe(O 3 PCH 3 )(C 2 O 4 ) 0.5 (H 2 O)] (1), has been synthesized under hydrothermal condition. The single-crystal X-ray diffraction studies reveal that 1 consists of layers of vertex-linked FeO 6 octahedra and O 3 PC tetrahedra, which are further connected by bis-chelate oxalate bridges, giving to a 3D structure with 10-membered channels. Crystal data: monoclinic, P2 1 /n (no. 14), a=4.851(2)A, b=16.803(7)A, c=7.941(4)A, β=107.516(6) o , V=617.2(5)A 3 , Z=4, R 1 =0.0337 and wR 2 =0.0874 for 1251 reflections [I>2σ(I)]. Mossbauer spectroscopy measurement confirms the existence of high-spin Fe(III) in 1. Magnetic studies show that 1 exhibits weak ferromagnetism with T N =30K due to a weak spin canting

Formation of large (≃100 μm ice crystals near the tropical tropopause

Directory of Open Access Journals (Sweden)

M. J. Alexander

2008-03-01

Full Text Available Recent high-altitude aircraft measurements with in situ imaging instruments indicated the presence of relatively large (≃100 μm length, thin (aspect ratios of ≃6:1 or larger hexagonal plate ice crystals near the tropical tropopause in very low concentrations (<0.01 L−1. These crystals were not produced by deep convection or aggregation. We use simple growth-sedimentation calculations as well as detailed cloud simulations to evaluate the conditions required to grow the large crystals. Uncertainties in crystal aspect ratio leave a range of possibilities, which could be constrained by knowledge of the water vapor concentration in the air where the crystal growth occurred. Unfortunately, water vapor measurements made in the cloud formation region near the tropopause with different instruments ranged from <2 ppmv to ≃3.5 ppmv. The higher water vapor concentrations correspond to very large ice supersaturations (relative humidities with respect to ice of about 200%. If the aspect ratios of the hexagonal plate crystals are as small as the image analysis suggests (6:1, see companion paper (Lawson et al., 2008 then growth of the large crystals before they sediment out of the supersaturated layer would only be possible if the water vapor concentration were on the high end of the range indicated by the different measurements (>3 ppmv. On the other hand, if the crystal aspect ratios are quite a bit larger (≃10:1, then H2O concentrations toward the low end of the measurement range (≃2–2.5 ppmv would suffice to grow the large crystals. Gravity-wave driven temperature and vertical wind perturbations only slightly modify the H2O concentrations needed to grow the crystals. We find that it would not be possible to grow the large crystals with water concentrations less than 2 ppmv, even with assumptions of a very high aspect ratio of 15 and steady upward motion of 2 cm s−1 to loft the crystals in the tropopause region. These calculations would seem

Studies on removal of plutonium from oxalic acid containing hydrochloric acid solutions

Energy Technology Data Exchange (ETDEWEB)

Ghadse, D R; Noronha, D M; Joshi, A R [Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai (India)

1994-06-01

Solution containing hydrochloric acid, oxalic acid and considerable quantities of plutonium may be generated while recycling of scrap produced during the metallic fuel fabrication. Plutonium from such waste is normally recovered by anion exchange method after the destruction of oxalic acid using suitable oxidising agent. Solvent extraction and ion exchange methods are being explored in this laboratory for recovery of Pu from oxalic acid containing HCl solutions without prior destruction of oxalic acid. This paper describes the results on the determination of distribution ratios for extraction of Pu(IV) from hydrochloric acid using Aliquot-336 or HDEHP under varying experimental conditions. (author). 5 refs., 5 tabs.

Influence of nutrition on feline calcium oxalate urolithiasis with emphasis on endogenous oxalate synthesis

NARCIS (Netherlands)

Dijcker, J.C.; Plantinga, E.A.; Baal, van J.; Hendriks, W.H.

2011-01-01

The prevalence of calcium oxalate (CaOx) uroliths detected in cats with lower urinary tract disease has shown a sharp increase over the last decades with a concomitant reciprocal decrease in the occurrence of struvite (magnesium ammonium phosphate) uroliths. CaOx stone-preventative diets are

Oxalate Mass Balance During Chemical Cleaning in Tank 5F

Energy Technology Data Exchange (ETDEWEB)

Poirier, M.; Fink, S.

2011-07-08

The Savannah River Site (SRS) is preparing Tank 5F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRS personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 5F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate.

Phytate (IP6) is a powerful agent for preventing calcifications in biological fluids: usefulness in renal lithiasis treatment.

Science.gov (United States)

Grases, F; Costa-Bauzá, A

1999-01-01

The extraordinary capacity of phytate (myo-inositol hexaphosphate), a substance present in blood, urine, interstitial and intracellular fluids, to inhibit crystallization of calcium salts (oxalate and phosphate) is discussed. Its role in preventing calcium renal stone formation is specifically presented and discussed. "In vitro" and "in vivo" experiments, as well as clinical studies clearly demonstrated that phytate plays an important role as a crystallization inhibitor of calcium salts in biological fluids and becomes a clear alternative in the treatment of calcium oxalate renal lithiasis.

Formation of 3D cholesterol crystals from 2D nucleation sites in lipid bilayer membranes: implications for atherosclerosis.

Science.gov (United States)

Varsano, Neta; Fargion, Iael; Wolf, Sharon G; Leiserowitz, Leslie; Addadi, Lia

2015-02-04

Atherosclerosis is the major precursor of cardiovascular disease. The formation of cholesterol crystals in atherosclerotic plaques is associated with the onset of acute pathology. The cholesterol crystals induce physical injury in the plaque core, promoting cell apoptosis and triggering an increased inflammatory response. Herein we address the question of how cholesterol crystal formation occurs in atherosclerosis. We demonstrate that three-dimensional (3D) cholesterol crystals can undergo directed nucleation from bilayer membranes containing two-dimensional (2D) cholesterol crystalline domains. We studied crystal formation on supported lipid bilayers loaded with exogenous cholesterol and labeled using a monoclonal antibody that specifically recognizes ordered cholesterol arrays. Our findings show that 3D crystals are formed exclusively on the bilayer regions where there are segregated 2D cholesterol crystalline domains and that they form on the domains. This study has potentially significant implications for our understanding of the crucial step in the mechanism by which atherosclerotic lesions form.

(Di­methyl­phosphor­yl)methanaminium hydrogen oxalate–oxalic acid (2/1)

OpenAIRE

Bialek, Sebastian; Clemens, Rebecca; Reiss, Guido J.

2014-01-01

The reaction of (di­methyl­phosphor­yl)methanamine (dpma) with oxalic acid in ethanol yielded the title solvated salt, C3H11NOP+·C2HO4 −·0.5C2H2O4. Its asymmetric unit consists of one dpmaH+ cation, one hydrogen oxalate anion and a half-mol­ecule of oxalic acid located around a twofold rotation axis. The H atom of the hydrogen oxalate anion is statistically disordered over two positions that are trans to each other. The hydrogen oxalate monoanion is not planar (bend angle ∼16°) whereas the ox...

Synthesis and characterization of new oxalate ester-polymer composites for practical applications

Energy Technology Data Exchange (ETDEWEB)

Petre, Razvan [Scientific Research Centre for CBRN Defense and Ecology, 225 Sos. Oltenitei, Bucharest 041309 (Romania); University POLITEHNICA of Bucharest, 149 Calea Victoriei, Bucharest 010072 (Romania); Zecheru, Teodora, E-mail: teodora.zecheru@yahoo.com [Scientific Research Centre for CBRN Defense and Ecology, 225 Sos. Oltenitei, Bucharest 041309 (Romania)

2013-03-15

The present study focused on the synthesis of high purity oxalate esters: bis(2,4,6-trichlorophenyl) oxalate (TCPO) and bis(2,4,5-trichloro-6-carbobutoxyphenyl) oxalate (TCCBPO), and further on their incorporation into potentially applicative polymer composites. The organic compounds were characterized through NMR and the composites obtained were evaluated for light capacity availability at room temperature and low temperatures. The concentrations of the peroxide, fluorescer, catalyst, and polymer additives were optimized. The chemiluminescent composites' performances were evaluated after 360 days and returned satisfactory results. - Highlights: Black-Right-Pointing-Pointer bis(2,4,6-Trichlorophenyl)-oxalate (TCPO) was synthesized. Black-Right-Pointing-Pointer bis(2,4,5-Trichloro-6-carbobutoxiphenyl)-oxalate (TCCBPO) was synthesized. Black-Right-Pointing-Pointer TCPO and TCCBPO-based composites were obtained. Black-Right-Pointing-Pointer The composites light emission was evaluated versus scotopic visual sensitivity. Black-Right-Pointing-Pointer The new compositions present superior performances within extensive emission time.

Synthesis and X-ray diffraction study of new uranyl malonate and oxalate complexes with carbamide

International Nuclear Information System (INIS)

Medvedkov, Ya. A.; Serezhkina, L. B.; Grigor’ev, M. S.; Serezhkin, V. N.

2016-01-01

Two new malonate-containing uranyl complexes with carbamide of the formulas [UO 2 (C 3 H 2 O 4 )(Urea) 2 ] (I) and [UO 2 (C 3 H 2 O 4 )(Urea) 3 ] (II), where Urea is carbamide, and one uranyl oxalate complex of the formula [UO 2 (C 2 O 4 )(Urea) 3 ] (III) were synthesized, and their crystals were studied by X-ray diffraction. The main structural units in crystals I are the electroneutral chains [UO 2 (C 3 H 2 O 4 )(Urea) 2 ] ∞ belonging to the crystal-chemical group AT 11 M 2 1 (A = UO 2 2+ , T 11 = C 3 H 2 O 4 2- , M 1 = Urea) of uranyl complexes. Crystals II and III are composed of the molecular complexes [UO 2 (L)(Urea) 3 ], where L = C 3 H 2 O 4 2- or C 2 O 4 2- , belonging to the crystal-chemical group AB 01 M 3 1 (A = UO 2 2+ , B 01 = C 3 H 2 O 4 2- or C 2 O 4 2- , M 1 = Urea). The characteristic features of the packing of the uranium-containing complexes are discussed in terms of molecular Voronoi–Dirichlet polyhedra. The effect of the Urea: U ratio on the structure of uranium-containing structural units is considered.

Enhanced nitrogen availability in karst ecosystems by oxalic acid release in the rhizosphere

Directory of Open Access Journals (Sweden)

Fujing ePan

2016-05-01

Full Text Available In karst ecosystems, a high level of CaCO3 enhances the stabilization of soil organic matter (SOM and causes nitrogen (N and/or phosphorus (P limitation in plants. Oxalic acid has been suggested to be involved in the nutrient-acquisition strategy of plants because its addition can temporarily relieve nutrient limitation. Therefore, understanding how oxalic acid drives N availability may help support successful vegetation restoration in the karst ecosystems of southwest China. We tested a model suggested by Clarholm et al. (2015 where oxalate reacts with Ca bridges in SOM, thus exposing previously protected areas to enzymatic attacks in a way that releases N for local uptake. We studied the effects of oxalic acid, microbial biomass C (MBC, and β-1,4-N-acetylglucosaminidase (NAG on potential N mineralization rates in rhizosphere soils of four plant species (two shrubs and two trees in karst areas. The results showed that rhizosphere soils of shrubs grown on formerly deforested land had significantly lower oxalic acid concentrations and NAG activity than that of trees in a 200-year-old forest. The levels of MBC in rhizosphere soils of shrubs were significantly lower than those of trees in the growing season, but the measure of shrubs and trees were similar in the non-growing season; the potential N mineralization rates showed a reverse pattern. Positive relationships were found among oxalic acid, MBC, NAG activity, and potential N mineralization rates for both shrubs and trees. This indicated that oxalic acid, microbes, and NAG may enhance N availability for acquisition by plants. Path analysis showed that oxalic acid enhanced potential N mineralization rates indirectly through inducing microbes and NAG activities. We found that the exudation of oxalic acid clearly provides an important mechanism that allows plants to enhance nutrient acquisition in karst ecosystems.

Enhanced Chemical Cleaning: Effectiveness Of The UV Lamp To Decompose Oxalates

International Nuclear Information System (INIS)

Ketusky, E.; Huff, T.; Sudduth, C.

2010-01-01

Enhanced Chemical Cleaning is a new process scheduled to begin cleaning Savannah River Site High Level Waste Tanks in 2012. It is an improvement over the current chemical cleaning method, in that it minimizes downstream impacts on the High Level Waste System. It is based on a state of the art scale removal process used on the secondary side of nuclear power plants, with modifications to accommodate the unique constraints created by the tanks. Both Enhanced Chemical Cleaning and the scale removal process are founded on dissolving metal oxides/hydroxides using oxalic acid, with subsequent oxalate decomposition via hydroxylation using ozone or peroxide, and UV light as a catalyst. A divergence Enhanced Chemical Cleaning has from nuclear power scale removal is the significantly increased solids concentration during oxalate decomposition. These solids can limit the ability of the UV light to create hydroxyl radicals, either by limiting the ability of the light to penetrate through the solution, or by increasing the fouling rate on the UV light. Both will decrease the overall catalytic effectiveness, thereby decreasing the concentration of formed hydroxyl radicals. The hydroxyl radicals are the driving force behind the oxalate decomposition. To understand the impact of increased solids, testing was performed using a medium pressure UV light inside an ozone supplied Oxalate Decomposition Reactor. Using a dissolved metal sludge simulant with an initial oxalate concentration greater than 12,000 ppm, and an initial pH of about 2.0, the spent acid solution was recirculated through the reactor, while the UV light was allowed to foul. For the first few hours, the oxalate decomposition rate was about 1,300 ppm/hour. After about 3 hours, enough time for the UV lamp to foul, the oxalate decomposition rate decreased to about 500 ppm/hour. The decomposition rate then remained roughly constant for the next 16 hours. Overall, testing showed that the oxalate destruction rate decreased

Measurement of plutonium oxalate in thermal neutron coincidence counters

International Nuclear Information System (INIS)

Marshall, R.S.; Erkkila, B.H.

1979-01-01

A coincidence neutron counting method has been developed for assaying batches of plutonium oxalate. Using counting data from two concentric rings of 3 He detectors, corrections are made for the effects that water has on the coincidence neutron count rate. Batches of plutonium oxalate varying from 750 to 1000 g of plutonium and from 34 to 54% water are assayed with an average accuracy of +-3%

Synthesis, structure and magnetic behavior of a new three-dimensional Manganese phosphite-oxalate: [C2N2H10][Mn2II(OH2)2(HPO3)2(C2O4)

International Nuclear Information System (INIS)

Ramaswamy, Padmini; Mandal, Sukhendu; Natarajan, Srinivasan

2009-01-01

A novel manganese phosphite-oxalate, [C 2 N 2 H 10 ][Mn 2 II (OH 2 ) 2 (HPO 3 ) 2 (C 2 O 4 )] has been hydothermally synthesized and its structure determined by single-crystal X-ray diffraction. The structure consists of neutral manganese phosphite layers, [Mn(HPO 3 )] ∞ , formed by MnO 6 octahedra and HPO 3 units, cross-linked by the oxalate moieties. The organic cations occupy the middle of the 8-membered one-dimensional channels. Magnetic studies indicate weak antiferromagnetic interactions between the Mn 2+ ions. - Abstract: A new antiferromagnetic three-dimensional inorganic-organic hybrid compound, [C 2 N 2 H 10 ][Mn 2 II (OH 2 ) 2 (HPO 3 ) 2 (C 2 O 4 )] has been prepared hydrothermally. The compound has neutral manganese layers pillared by oxalate units. The neutral manganese layers are shown here. Display Omitted

New Paradigm for Plasma Crystal Formation with weak grain interaction

International Nuclear Information System (INIS)

Tsytovich, V.N.; Morfill, G.E.

2005-01-01

New results for non-linear grain screening, non-linear ion drag and non-linear collective attractions appropriate for existing experiments are used for the first time together to explain the observed phenomena of plasma condensation. Based on the physics of collective non-linear grain attraction a paradigm for plasma crystal formation is formulated according to which plasma the crystal formation is due to localization of grains in weak non-linear collective attraction wells. Nonlinearity in screening is an important feature of new paradigm and takes into account that the grain charges are large. The physical consequence of large non-linearity is the presence of relative large attraction potential well at distances several times larger then the non-linear screening radius. Calculated location of the potential well is of the order of the observed inter-grain distances in plasma crystals and the calculated deepness of the potential well determining the temperature of phase transition is close to that observed. The calculations of the deepness of the attraction collective well and the critical value of the coupling constant are performed using an assumption that the collective attraction length is larger than the non-linear screening length. The concept of collective grain interaction in complex plasmas is considered for the case where the non-linear screening is fully determining the collective attraction well

Corrosion and impedance studies on magnesium alloy in oxalate solution

Energy Technology Data Exchange (ETDEWEB)

Fekry, A.M., E-mail: hham4@hotmail.com [Chemistry Department, Faculty of Science, Cairo University, Gamaa Street, Giza 12613 (Egypt); Tammam, Riham H. [Chemistry Department, Faculty of Science, Cairo University, Gamaa Street, Giza 12613 (Egypt)

2011-06-15

Highlights: > Corrosion behavior of AZ91E alloy was investigated in 0.1 M Na{sub 2}C{sub 2}O{sub 4} containing different additives as Br{sup -}, Cl{sup -} or Silicate. > The corrosion rate of 0.1 M oxalate solution containing silicate ion is lower than the blank (0.1 M Na{sub 2}C{sub 2}O{sub 4}). This was confirmed by scanning electron microscope (SEM) observations. > For the other added ions Br{sup -} or Cl{sup -}, the corrosion rate is higher than the blank. - Abstract: Corrosion behavior of AZ91E alloy was investigated in oxalate solution using potentiodynamic polarization and electrochemical impedance measurements (EIS). The effect of oxalate concentration was studied, where the corrosion rate increases with increasing oxalate concentration. The effect of added ions (Br{sup -}, Cl{sup -} or SiO{sub 3}{sup 2-}) on the electrochemical behavior of magnesium alloy in 0.1 M Na{sub 2}C{sub 2}O{sub 4} solution at 298 K, was investigated. It was found that the corrosion rate of 0.1 M oxalate solution containing silicate ion is lower than the blank (0.1 M Na{sub 2}C{sub 2}O{sub 4}). This was confirmed by scanning electron microscope (SEM) observations. However, for the other added ions Br{sup -} or Cl{sup -}, the corrosion rate is higher than the blank.

Formation of Coulomb crystal in presence of attractive overlapping Debye sphere potential

International Nuclear Information System (INIS)

Baruah, Swati; Das, Nilakshi

2011-01-01

The role of attractive overlapping Debye sphere (ODS) potential on dust crystal formation has been investigated by using molecular dynamics code. A comparative study on plasma crystal formation has been made between Yukawa and coupled Yukawa-ODS potential by calculating pair-correlation function, for different values of Coulomb coupling parameter Γ and screening parameter κ. From our study, it is seen that the attractive ODS potential becomes dominant beyond a critical radius than that of the Yukawa potential. This leads to the fact that the effect due to combined Yukawa-ODS potential depends more sensitively on κ. From the comparison of the results for Yukawa and ODS potential with experimental results, it is observed that a close agreement is obtained for attractive ODS potential.

Influence of anodization parameters on the volume expansion of anodic aluminum oxide formed in mixed solution of phosphoric and oxalic acids

Science.gov (United States)

Kao, Tzung-Ta; Chang, Yao-Chung

2014-01-01

The growth of anodic alumina oxide was conducted in the mixed solution of phosphoric and oxalic acids. The influence of anodizing voltage, electrolyte temperature, and concentration of phosphoric and oxalic acids on the volume expansion of anodic aluminum oxide has been investigated. Either anodizing parameter is chosen to its full extent of range that allows the anodization process to be conducted without electric breakdown and to explore the highest possible volume expansion factor. The volume expansion factors were found to vary between 1.25 and 1.9 depending on the anodizing parameters. The variation is explained in connection with electric field, ion transport number, temperature effect, concentration, and activity of acids. The formation of anodic porous alumina at anodizing voltage 160 V in 1.1 M phosphoric acid mixed with 0.14 M oxalic acid at 2 °C showed the peak volume expansion factor of 1.9 and the corresponding moderate growth rate of 168 nm/min.

Matrix Gla Protein is Involved in Crystal Formation in Kidney of Hyperoxaluric Rats

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Xiuli Lu

2013-02-01

Full Text Available Background: Matrix Gla protein (MGP is a molecular determinant regulating vascular calcification of the extracellular matrix. However, it is still unclear how MGP may be invovled in crystal formation in the kidney of hyperoxaluric rats. Methods: Male Sprague-Dawley rats were divided into the hyperoxaluric group and control group. Hyperoxaluric rats were administrated by 0.75% ethylene glycol (EG for up to 8 weeks. Renal MGP expression was detected by the standard avidin-biotin complex (ABC method. Renal crystal deposition was observed by a polarizing microscope. Total RNA and protein from the rat kidney tissue were extracted. The levels of MGP mRNA and protein expression were analyzed by the real-time polymerase chain reaction (RT-PCR and Western blot. Results: Hyperoxaluria was induced successfully in rats. The MGP was polarly distributed, on the apical membrane of renal tubular epithelial cells, and was found in the ascending thick limbs of Henle's loop (cTAL and the distal convoluted tubule (DCT in hyperoxaluric rats, its expression however, was present in the medullary collecting duct (MCD in stone-forming rats. Crystals with multilaminated structure formed in the injurious renal tubules with lack of MGP expression.MGP mRNA expression was significantly upregulated by the crystals' stimulations. Conclusion: Our results suggested that the MGP was involved in crystals formation by the continuous expression, distributing it polarly in the renal tubular cells and binding directly to the crystals.

Synthesis and characteristics of a novel 3-D organic amine oxalate: (enH2)1.5[Bi3(C2O4)6(CO2CONHCH2CH2NH3)].6.5H2O

International Nuclear Information System (INIS)

Yu Xiaohong; Zhang Hanhui; Cao Yanning; Chen Yiping; Wang Zhen

2006-01-01

A novel 3-D compound of (enH 2 ) 1.5 [Bi 3 (C 2 O 4 ) 6 (CO 2 CONHCH 2 CH 2 NH 3 )].6.5H 2 O has been hydrothermally synthesized and characterized by IR, ultraviolet-visible diffuse reflection integral spectrum (UV-Vis DRIS), fluorescence spectra, TGA and single crystal X-ray diffraction. It crystallizes in the monoclinic system, space group C2/c with a=31.110(8)A, b=11.544(3)A, c=22.583(6)A, β=112.419(3) o , V=7497(3)A 3 , Z=8, R 1 =0.0463 and wR 2 =0.1393 for unique 7686 reflections I>2σ(I). In the title compound, the Bi atoms have eight-fold and nine-fold coordination with respect to the oxygen atoms, with the Bi atoms in distorted dodecahedron and monocapped square antiprism, respectively. The 3-D framework of the title compound contains channels and is composed of linkages between Bi atoms and oxalate units, forming honeycomb-like layers with two kinds of 6+6 membered aperture, and pillared by oxalate ligands and monamide groups. The channels have N-ethylamine oxalate monamide group - CO 2 CONHCH 2 CH 2 NH 3 + , which is formed by the in situ reaction of en and oxalate acid. At room temperature, the complex exhibits intense blue luminescence with an emission peak at 445nm

Photorefractive grating formation in piezoelectric La3Ga5SiO14:Pr3+ crystals

DEFF Research Database (Denmark)

Dam-Hansen, C.; Johansen, P.M.; Fridkin, V.M.

1996-01-01

Photorefractive grating formation and erasure in piezoelectric crystals of La3Ga5SiO14:Pr3+ are presented. The specific photoconductivity and the photorefractive sensitivity are determined. The polarization dependence of the grating formation due to the bulk photovoltaic effect is shown and compa......Photorefractive grating formation and erasure in piezoelectric crystals of La3Ga5SiO14:Pr3+ are presented. The specific photoconductivity and the photorefractive sensitivity are determined. The polarization dependence of the grating formation due to the bulk photovoltaic effect is shown...... and compared favorably with the theoretical expression. This photorefractive material provides a possibility for separate investigations of the charge migration processes responsible for the photorefractive effect. (C) 1996 American Institute of Physics....

Enzymatic oxalic acid regulation correlated with wood degradation in four brown-rot fungi

Science.gov (United States)

Anne Christine Steenkjær Hastrup; Frederick Green III; Patricia K. Lebow; Bo Jensen

2012-01-01

Oxalic acid is a key component in the initiation of brown-rot decay and it has been suggested that it plays multiple roles during the degradation process. Oxalic acid is accumulated to varying degrees among brown-rot fungi; however, details on active regulation are scarce. The accumulation of oxalic acid was measured in this study from wood degraded by the four brown-...

Formation of nano-hydroxyapatite crystal in situ in chitosan-pectin polyelectrolyte complex network

International Nuclear Information System (INIS)

Li Junjie; Zhu Dunwan; Yin Jianwei; Liu Yuxi; Yao Fanglian; Yao Kangde

2010-01-01

Hydroxyapatite (HA)/polysaccharide composites have been widely used in bone tissue engineering due to their chemical similarity to natural bone. Polymer matrix-mediated synthesis of nano-hydroxyapatite is one of the simplest models for biomimetic. In this article, the nano-hydroxyapatite/chitosan-pectin (nHCP) composites were prepared through in situ mineralization of hydroxyapatite in chitosan-pectin polyelectrolyte complex (PEC) network. The formation processes of nHCP were investigated by X-ray diffraction (XRD) analysis. The interactions between nHA crystal and chitosan-pectin PEC networks were studied using Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). The morphology and structure of nHA crystal were characterized by XRD and Transmission Electron Microscope (TEM). Results suggested that the interfacial interactions between nano-hydroxyapatite crystal and chitosan-pectin PEC network assist the site specific nucleation and growth of nHA nanoparticles. The nHA crystals grow along the c-axis. In this process, pH value is the main factor to control the nucleation and growth of nHA crystal in chitosan-pectin PEC networks, because both the interactions' strength between nHA crystal and chitosan-pectin and diffusion rate of inorganic ions depend on the pH value of the reaction system. Apart from the pH value, the chitosan/pectin ratio and [Ca 2+ ] also take important effects on the formation of nHA crystal. An effective way to control the size of nHA crystal is to adjust the content of pectin and [Ca 2+ ]. It is interesting that the Zeta potential of nHCP composites is about - 30 mV when the chitosan/pectin ratio ≤ 1:1, and the dispersion solution of nHCP composites has higher stability, which provides the possibility to prepare 3D porous scaffolds with nHCP for bone tissue engineering.

Formation of nano-hydroxyapatite crystal in situ in chitosan-pectin polyelectrolyte complex network

Energy Technology Data Exchange (ETDEWEB)

Li Junjie [Department of Polymer Science and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 (China); Research Institute of Polymeric Materials, Tianjin University, Tianjin, 300072 (China); Zhu Dunwan [Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, 300072 (China); Yin Jianwei; Liu Yuxi [Department of Polymer Science and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 (China); Yao Fanglian, E-mail: yaofanglian@tju.edu.cn [Department of Polymer Science and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 (China); Yao Kangde [Research Institute of Polymeric Materials, Tianjin University, Tianjin, 300072 (China)

2010-07-20

Hydroxyapatite (HA)/polysaccharide composites have been widely used in bone tissue engineering due to their chemical similarity to natural bone. Polymer matrix-mediated synthesis of nano-hydroxyapatite is one of the simplest models for biomimetic. In this article, the nano-hydroxyapatite/chitosan-pectin (nHCP) composites were prepared through in situ mineralization of hydroxyapatite in chitosan-pectin polyelectrolyte complex (PEC) network. The formation processes of nHCP were investigated by X-ray diffraction (XRD) analysis. The interactions between nHA crystal and chitosan-pectin PEC networks were studied using Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). The morphology and structure of nHA crystal were characterized by XRD and Transmission Electron Microscope (TEM). Results suggested that the interfacial interactions between nano-hydroxyapatite crystal and chitosan-pectin PEC network assist the site specific nucleation and growth of nHA nanoparticles. The nHA crystals grow along the c-axis. In this process, pH value is the main factor to control the nucleation and growth of nHA crystal in chitosan-pectin PEC networks, because both the interactions' strength between nHA crystal and chitosan-pectin and diffusion rate of inorganic ions depend on the pH value of the reaction system. Apart from the pH value, the chitosan/pectin ratio and [Ca{sup 2+}] also take important effects on the formation of nHA crystal. An effective way to control the size of nHA crystal is to adjust the content of pectin and [Ca{sup 2+}]. It is interesting that the Zeta potential of nHCP composites is about - 30 mV when the chitosan/pectin ratio {<=} 1:1, and the dispersion solution of nHCP composites has higher stability, which provides the possibility to prepare 3D porous scaffolds with nHCP for bone tissue engineering.

A Novel Method for Fabricating Double Layers Porous Anodic Alumina in Phosphoric/Oxalic Acid Solution and Oxalic Acid Solution

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Yanfang Xu

2016-01-01

Full Text Available A novel method for fabricating ordered double layers porous anodic alumina (DL-PAA with controllable nanopore size was presented. Highly ordered large pore layer with interpore distance of 480 nm was fabricated in phosphoric acid solution with oxalic acid addition at the potential of 195 V and the small pore layer was fabricated in oxalic acid solution at the potential from 60 to 100 V. Experimental results show that the thickness of large pore layer is linearly correlative with anodizing time, and pore diameter is linearly correlative with pore widening time. When the anodizing potential in oxalic acid solution was adjusted from 60 to 100 V, the small pore layers with continuously tunable interpore distance from 142 to 241 nm and pore density from 1.94×109 to 4.89×109 cm−2 were obtained. And the interpore distance and the pore density of small pore layers are closely correlative with the anodizing potential. The fabricated DL-PAA templates can be widely utilized for fabrication of ordered nanomaterials, such as superhydrophobic or gecko-inspired adhesive materials and metal or semiconductor nanowires.

Hygroscopic behavior and chemical composition evolution of internally mixed aerosols composed of oxalic acid and ammonium sulfate

Science.gov (United States)

Wang, Xiaowei; Jing, Bo; Tan, Fang; Ma, Jiabi; Zhang, Yunhong; Ge, Maofa

2017-10-01

Although water uptake of aerosol particles plays an important role in the atmospheric environment, the effects of interactions between components on chemical composition and hygroscopicity of particles are still not well constrained. The hygroscopic properties and phase transformation of oxalic acid (OA) and mixed particles composed of ammonium sulfate (AS) and OA with different organic to inorganic molar ratios (OIRs) have been investigated by using confocal Raman spectroscopy. It is found that OA droplets first crystallize to form OA dihydrate at 71 % relative humidity (RH), and further lose crystalline water to convert into anhydrous OA around 5 % RH during the dehydration process. The deliquescence and efflorescence point for AS is determined to be 80.1 ± 1.5 % RH and 44.3 ± 2.5 % RH, respectively. The observed efflorescence relative humidity (ERH) for mixed OA / AS droplets with OIRs of 1 : 3, 1 : 1 and 3 : 1 is 34.4 ± 2.0, 44.3 ± 2.5 and 64.4 ± 3.0 % RH, respectively, indicating the elevated OA content appears to favor the crystallization of mixed systems at higher RH. However, the deliquescence relative humidity (DRH) of AS in mixed OA / AS particles with OIRs of 1 : 3 and 1 : 1 is observed to occur at 81.1 ± 1.5 and 77 ± 1.0 % RH, respectively. The Raman spectra of mixed OA / AS droplets indicate the formation of ammonium hydrogen oxalate (NH4HC2O4) and ammonium hydrogen sulfate (NH4HSO4) from interactions between OA and AS in aerosols during the dehydration process on the time scale of hours, which considerably influence the subsequent deliquescence behavior of internally mixed particles with different OIRs. The mixed OA / AS particles with an OIR of 3 : 1 exhibit no deliquescence transition over the RH range studied due to the considerable transformation of (NH4)2SO4 into NH4HC2O4 with a high DRH. Although the hygroscopic growth of mixed OA / AS droplets is comparable to that of AS or OA at high RH during the dehydration process, Raman growth

Influence of oxalic acid on the dissolution kinetics of manganese oxide

Science.gov (United States)

Godunov, E. B.; Artamonova, I. V.; Gorichev, I. G.; Lainer, Yu. A.

2012-11-01

The kinetics and electrochemical processes of the dissolution of manganese oxides with various oxidation states in sulfuric acid solutions containing oxalate ion additives is studied under variable conditions (concentration, pH, temperature). The parameters favoring a higher degree of the dissolution of manganese oxides in acidic media are determined. The optimal conditions are found for the dissolution of manganese oxides in acidic media in the presence of oxalate ions. The mechanism proposed for the dissolution of manganese oxides in sulfuric acid solutions containing oxalic acid is based on the results of kinetic and electrochemical studies. The steps of the dissolution mechanism are discussed.

ENHANCED CHEMICAL CLEANING: EFFECTIVENESS OF THE UV LAMP TO DECOMPOSE OXALATES

Energy Technology Data Exchange (ETDEWEB)

Ketusky, E.; Huff, T.; Sudduth, C.

2010-01-19

Enhanced Chemical Cleaning is a new process scheduled to begin cleaning Savannah River Site High Level Waste Tanks in 2012. It is an improvement over the current chemical cleaning method, in that it minimizes downstream impacts on the High Level Waste System. It is based on a state of the art scale removal process used on the secondary side of nuclear power plants, with modifications to accommodate the unique constraints created by the tanks. Both Enhanced Chemical Cleaning and the scale removal process are founded on dissolving metal oxides/hydroxides using oxalic acid, with subsequent oxalate decomposition via hydroxylation using ozone or peroxide, and UV light as a catalyst. A divergence Enhanced Chemical Cleaning has from nuclear power scale removal is the significantly increased solids concentration during oxalate decomposition. These solids can limit the ability of the UV light to create hydroxyl radicals, either by limiting the ability of the light to penetrate through the solution, or by increasing the fouling rate on the UV light. Both will decrease the overall catalytic effectiveness, thereby decreasing the concentration of formed hydroxyl radicals. The hydroxyl radicals are the driving force behind the oxalate decomposition. To understand the impact of increased solids, testing was performed using a medium pressure UV light inside an ozone supplied Oxalate Decomposition Reactor. Using a dissolved metal sludge simulant with an initial oxalate concentration greater than 12,000 ppm, and an initial pH of about 2.0, the spent acid solution was recirculated through the reactor, while the UV light was allowed to foul. For the first few hours, the oxalate decomposition rate was about 1,300 ppm/hour. After about 3 hours, enough time for the UV lamp to foul, the oxalate decomposition rate decreased to about 500 ppm/hour. The decomposition rate then remained roughly constant for the next 16 hours. Overall, testing showed that the oxalate destruction rate decreased

The effect of citric and oxalic acid doping on the superconducting properties of MgB2

International Nuclear Information System (INIS)

Ojha, N; Singla, Rashmi; Varma, G D; Malik, V K; Bernhard, C

2009-01-01

In this paper we report the effect of carbon doping on the structural and superconducting properties of MgB 2 using citric and oxalic acids as carbon sources. The bulk polycrystalline samples have been synthesized via a standard solid state reaction route with composition MgB 2 +x wt% of citric and oxalic acids (x = 0, 5 and 10). The x-ray diffraction results reveal the formation of dominantly MgB 2 with only a small amount of impurity phase MgO and substitution of C at the B site of MgB 2 for both dopants. Improvements in the upper critical field (H C2 ), irreversibility field (H irr ) and high field (>2.5 T) critical current density (J C ) have been observed on C doping in the samples. The correlations between superconducting properties and structural characteristics of the samples are described and discussed in this paper.

High-performing mesoporous iron oxalate anodes for lithium-ion batteries.

Science.gov (United States)

Ang, Wei An; Gupta, Nutan; Prasanth, Raghavan; Madhavi, Srinivasan

2012-12-01

Mesoporous iron oxalate (FeC(2)O(4)) with two distinct morphologies, i.e., cocoon and rod, has been synthesized via a simple, scalable chimie douce precipitation method. The solvent plays a key role in determining the morphology and microstructure of iron oxalate, which are studied by field-emission scanning electron microscopy and high-resolution transmission electron microscopy. Crystallographic characterization of the materials has been carried out by X-ray diffraction and confirmed phase-pure FeC(2)O(4)·2H(2)O formation. The critical dehydration process of FeC(2)O(4)·2H(2)O resulted in anhydrous FeC(2)O(4), and its thermal properties are studied by thermogravimetric analysis. The electrochemical properties of anhydrous FeC(2)O(4) in Li/FeC(2)O(4) cells are evaluated by cyclic voltammetry, galvanostatic charge-discharge cycling, and electrochemical impedance spectroscopy. The studies showed that the initial discharge capacities of anhydrous FeC(2)O(4) cocoons and rods are 1288 and 1326 mA h g(-1), respectively, at 1C rate. Anhydrous FeC(2)O(4) cocoons exhibited stable capacity even at high C rates (11C). The electrochemical performance of anhydrous FeC(2)O(4) is found to be greatly influenced by the number of accessible reaction sites, morphology, and size effects.

Precipitation stripping of neodymium from carboxylate extractant with aqueous oxalic acid solutions

International Nuclear Information System (INIS)

Konishi, Yasuhiro; Asai, Satoru; Murai, Tetuya

1993-01-01

This paper describes a precipitation stripping method in which neodymium ions are stripped from carboxylate extractant in organic solvent and simultaneously precipitated with aqueous oxalic acid solution. For the single-stage process, a quantitative criterion for precipitating oxalate powders was derived theoretically, and stripping experiments were done under the precipitation conditions. The resultant precipitates were neodymium oxalate, which is completely free from contamination by the carboxylate extractant and the organic solvent. The overall rate of stripping was controlled by the transfer of neodymium carboxylate in the organic solution, indicating that the presence of oxalic acid in the aqueous phase has no effect on the stripping rate. These findings demonstrate the feasibility of combining the conventional stripping and precipitation stages in a solvent extraction process for separation and purification of rare earths

Formation of anorthosite on the Moon through magma ocean fractional crystallization

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Tatsuyuki Arai

2017-03-01

Full Text Available Lunar anorthosite is a major rock of the lunar highlands, which formed as a result of plagioclase-floatation in the lunar magma ocean (LMO. Constraints on the sufficient conditions that resulted in the formation of a thick pure anorthosite (mode of plagioclase >95 vol.% is a key to reveal the early magmatic evolution of the terrestrial planets. To form the pure lunar anorthosite, plagioclase should have separated from the magma ocean with low crystal fraction. Crystal networks of plagioclase and mafic minerals develop when the crystal fraction in the magma (φ is higher than ca. 40–60 vol.%, which inhibit the formation of pure anorthosite. In contrast, when φ is small, the magma ocean is highly turbulent, and plagioclase is likely to become entrained in the turbulent magma rather than separated from the melt. To determine the necessary conditions in which anorthosite forms from the LMO, this study adopted the energy criterion formulated by Solomatov. The composition of melt, temperature, and pressure when plagioclase crystallizes are constrained by using MELTS/pMELTS to calculate the density and viscosity of the melt. When plagioclase starts to crystallize, the Mg# of melt becomes 0.59 at 1291 °C. The density of the melt is smaller than that of plagioclase for P > 2.1 kbar (ca. 50 km deep, and the critical diameter of plagioclase to separate from the melt becomes larger than the typical crystal diameter of plagioclase (1.8–3 cm. This suggests that plagioclase is likely entrained in the LMO just after the plagioclase starts to crystallize. When the Mg# of melt becomes 0.54 at 1263 °C, the density of melt becomes larger than that of plagioclase even for 0 kbar. When the Mg# of melt decreases down to 0.46 at 1218 °C, the critical diameter of plagioclase to separate from the melt becomes 1.5–2.5 cm, which is nearly equal to the typical plagioclase of the lunar anorthosite. This suggests that plagioclase could separate from the

Influence of crystal orientation on the formation of femtosecond laser-induced periodic surface structures and lattice defects accumulation

Energy Technology Data Exchange (ETDEWEB)

Sedao, Xxx; Garrelie, Florence, E-mail: florence.garrelie@univ-st-etienne.fr; Colombier, Jean-Philippe; Reynaud, Stéphanie; Pigeon, Florent [Université de Lyon, CNRS, UMR5516, Laboratoire Hubert Curien, Université de Saint Etienne, Jean Monnet, F-42023 Saint-Etienne (France); Maurice, Claire; Quey, Romain [Ecole Nationale Supérieure des Mines de Saint-Etienne, CNRS, UMR5307, Laboratoire Georges Friedel, F-42023 Saint-Etienne (France)

2014-04-28

The influence of crystal orientation on the formation of femtosecond laser-induced periodic surface structures (LIPSS) has been investigated on a polycrystalline nickel sample. Electron Backscatter Diffraction characterization has been exploited to provide structural information within the laser spot on irradiated samples to determine the dependence of LIPSS formation and lattice defects (stacking faults, twins, dislocations) upon the crystal orientation. Significant differences are observed at low-to-medium number of laser pulses, outstandingly for (111)-oriented surface which favors lattice defects formation rather than LIPSS formation.

Removal of plutonium from nitric acid-oxalic acid solutions using anion exchange method

International Nuclear Information System (INIS)

Kasar, U.M.; Pawar, S.M.; Joshi, A.R.

1999-01-01

An anion exchange method using Amberlyst A-26 (MP) resin was developed for removal of Pu from nitric acid-oxalic acid solutions without destroying oxalate. The method consists of sorption of Pu(IV) on Amberlyst A-26, a macroporous anion exchange resin, from nitric acid-oxalic acid medium in the presence of Al(NO 3 ) 3 . Pu(IV) breakthrough capacity of Amberlyst A-26 using synthetic feed solution was determined. (author)

Formation of assimilable organic carbon during oxidation of natural waters with ozone, chlorine dioxide, chlorine, permanganate, and ferrate.

Science.gov (United States)

Ramseier, Maaike K; Peter, Andreas; Traber, Jacqueline; von Gunten, Urs

2011-02-01

Five oxidants, ozone, chlorine dioxide, chlorine, permanganate, and ferrate were studied with regard to the formation of assimilable organic carbon (AOC) and oxalate in absence and presence of cyanobacteria in lake water matrices. Ozone and ferrate formed significant amounts of AOC, i.e. more than 100 μg/L AOC were formed with 4.6 mg/L ozone and ferrate in water with 3.8 mg/L dissolved organic carbon. In the same water samples chlorine dioxide, chlorine, and permanganate produced no or only limited AOC. When cyanobacterial cells (Aphanizomenon gracile) were added to the water, an AOC increase was detected with ozone, permanganate, and ferrate, probably due to cell lysis. This was confirmed by the increase of extracellular geosmin, a substance found in the selected cyanobacterial cells. AOC formation by chlorine and chlorine dioxide was not affected by the presence of the cells. The formation of oxalate upon oxidation was found to be a linear function of the oxidant consumption for all five oxidants. The following molar yields were measured in three different water matrices based on oxidant consumed: 2.4-4.4% for ozone, 1.0-2.8% for chlorine dioxide and chlorine, 1.1-1.2% for ferrate, and 11-16% for permanganate. Furthermore, oxalate was formed in similar concentrations as trihalomethanes during chlorination (yield ∼ 1% based on chlorine consumed). Oxalate formation kinetics and stoichiometry did not correspond to the AOC formation. Therefore, oxalate cannot be used as a surrogate for AOC formation during oxidative water treatment. Copyright © 2010 Elsevier Ltd. All rights reserved.

Investigation of the cluster formation in lithium niobate crystals by computer modeling method

Energy Technology Data Exchange (ETDEWEB)

Voskresenskii, V. M.; Starodub, O. R., E-mail: ol-star@mail.ru; Sidorov, N. V.; Palatnikov, M. N. [Russian Academy of Sciences, Tananaev Institute of Chemistry and Technology of Rare Earth Elements and Mineral Raw Materials, Kola Science Centre (Russian Federation)

2017-03-15

The processes occurring upon the formation of energetically equilibrium oxygen-octahedral clusters in the ferroelectric phase of a stoichiometric lithium niobate (LiNbO{sub 3}) crystal have been investigated by the computer modeling method within the semiclassical atomistic model. An energetically favorable cluster size (at which a structure similar to that of a congruent crystal is organized) is shown to exist. A stoichiometric cluster cannot exist because of the electroneutrality loss. The most energetically favorable cluster is that with a Li/Nb ratio of about 0.945, a value close to the lithium-to-niobium ratio for a congruent crystal.

Determination of Food Oxalates Using Silica–Titania Xerogel Modified with Eriochrome Cyanine R

Directory of Open Access Journals (Sweden)

Maria A. Morosanova

2018-03-01

Full Text Available The interaction of silica–titania xerogel with triphenylmethane dyes (pyrocatechol violet, chrome azurol S, eriochrome cyanine R has been investigated to create a new sensor material for solid phase spectrophotometric determination of food oxalates. The complex forming reaction between xerogel incorporated titanium(IV and triphenylmethane dyes has been studied; half-reaction periods, complex composition, equilibrium constants, and xerogel sorption capacity have been calculated for each dye. Eriochrome cyanine R (ECR is characterized by the shortest half-reaction period, the smallest equilibrium constant, and the greatest capacity; it has been chosen for the sensor material construction because titanium(IV-ECR complex is formed faster and can be destroyed easier than other studied complexes. The interaction of this sensor material with oxalates has been described: the presence of oxalates causes sensor material discoloration and the absorbance is used as analytical signal. The analytical range is 35–900 mg/L (LOD 10.5 mg/L, n = 7. High concentrations of interfering inorganic anions, organic acids, and sucrose did not affect oxalate determination. Proposed solid phase spectrophotometric procedure has been successfully applied for the determination of oxalates in food samples (sorrel, spinach, parsley, ginger, and black pepper and the results are in good agreement with HPLC oxalate determination.

Effects of potassium oxalate on knoop hardness of etch-and-rinse adhesives.

Science.gov (United States)

Silva, S M A; Malacarne-Zanon, J; Carvalho, R M; Alves, M C; De Goes, M F; Anido-Anido, A; Carrilho, M R

2012-01-01

The objective of this study was to determine whether the hardness of etch-and-rinse adhesives may be affected by the pretreatment of acid-etched dentin with potassium oxalate desensitizer. Unerupted human third molars were cut into crown segments by removing the occlusal enamel and roots. The pulp chamber of these crown segments was connected to a syringe barrel filled with phosphate-buffered saline so that the moisture of dentin was maintained during the bonding procedures. Three etch-and-rinse adhesives-two two-step systems (Adper Single Bond 2 [SB], One-Step [OS]) and one three-step system (Adper Scotchbond Multi-Purpose [MP])-were applied to acid-etched dentin that had been treated (experimental groups) or not (control groups) with potassium oxalate (BisBlock). The Knoop hardness (KHN) of adhesives was taken at different sites of the outer surface of the adhesive-bonded dentin. The KHN of the three tested adhesives applied to acid-etched dentin treated with potassium oxalate was significantly lower than that exhibited by the respective controls (not treated with oxalate; padhesive, the treatment with potassium oxalate reduced the adhesives' KHN (psystem exhibiting the lowest KHN compared with the MP and SB systems.

Effect of animal and vegetable protein intake on oxalate excretion in idiopathic calcium stone disease.

Science.gov (United States)

Marangella, M; Bianco, O; Martini, C; Petrarulo, M; Vitale, C; Linari, F

1989-04-01

Oxalate excretion was measured in healthy subjects and idiopathic calcium stone-formers on dietary regimens which differed in the type and amount of protein allowed; 24-h urine collections were obtained from 41 practising vegetarians and 40 normal persons on a free, mixed, "mediterranean" diet. Twenty idiopathic calcium stone-formers were also studied while on two low calcium, low oxalate diets which differed in that animal protein was high in one and restricted in the other. Vegetarians had higher urinary oxalate levels than controls and although the calcium levels were markedly lower, urinary saturation with calcium/oxalate was significantly higher. This mild hypercalciuria was interpreted as being secondary to both a higher intake and increased fractional intestinal absorption of oxalate. Changing calcium stone-formers from a high to a low animal protein intake produced a significant decrease in calcium excretion but there was no variation in urinary oxalate. As a result, the decrease in calcium oxalate saturation was only marginal and not significant. It was concluded that dietary animal protein has a minimal effect on oxalate excretion. Mild hyperoxaluria of idiopathic calcium stone disease is likely to be intestinal in origin. Calcium stone-formers should be advised to avoid an excess of animal protein but the risks of a vegetable-rich diet should also be borne in mind.

Oxalic acid biosynthesis is encoded by an operon in Burkholderia glumae

Science.gov (United States)

Although the biosynthesis of oxalic acid is known to occur in a number of bacteria, the mechanism(s) regulating its production remains largely unknown. To date, there is no report on the identification of an oxalic acid biosynthetic pathway gene from bacteria. In an attempt to identify such a gene...

Influence of submelting on formation of single crystals of nickel alloy with cellular-dendritic structure

International Nuclear Information System (INIS)

Pankin, G.N.; Esin, V.O.; Ponomarev, V.V.

1996-01-01

A study was made into specific features of cellular - dendritic structure formation in single crystals of nickel base alloy ZhS26 which had been crystallized following the pattern of solid solution. The single crystals in growing were subjected to periodic partial remelting to suppress the transition of cellular structure into a cellular - dendritic one during directional solidification. The results obtained showed the possibility to stabilize cellular growth of solid solution by way of inversion of interphase surface motion in the process of directional crystallization. 4 refs.; 5 figs

Viscosities of oxalic acid and its salts in water and binary aqueous ...

Indian Academy of Sciences (India)

Unknown

Viscosities; oxalic acid and its salts; water + THF mixtures; structure-breakers. 1. Introduction ... has found its application in the organic syntheses as manifested from ... water. In other words, these results indicate that oxalic acid and its salts mix ...

Effect of processing and cooking on total and soluble oxalate content in frozen root vegetables prepared for consumption

Directory of Open Access Journals (Sweden)

Z. LISIEWSKA

2008-12-01

Full Text Available The oxalate content of beetroot, carrot, celeriac and parsnip after freezing by traditional and modified methods (the latter resulting in a convenience food product, and after the preparation of frozen products for consumption was evaluated. The highest content of total and soluble oxalates (105 and 82 mg 100 g-1 fresh matter was found in beetroot. The lowest proportion (55% of soluble oxalates was noted in celeriac; this proportion was higher in the remaining vegetables, being broadly similar for each of them. Blanching brought about a significant decrease in total and soluble oxalates in fresh vegetables. Cooking resulted in a higher loss of oxalates. The level of oxalates in products prepared for consumption directly after freezing approximated that before freezing. Compared with the content before freezing, vegetables prepared for consumption by cooking after frozen storage contained less oxalates, except for total oxalates in parsnip and soluble oxalates in beetroot and celeriac. The highest ratio of oxalates to calcium was found in raw beetroot; it was two times lower in raw carrot; five times lower in raw celeriac; and eight times lower in raw parsnip. These ratios were lower after technological and culinary processing. The percentage of oxalate bound calcium depended on the species; this parameter was not significantly affected by the procedures applied. The true retention of oxalates according to Judprasong et al. (2006 was lower than retention calculated taking its content in 100 g fresh matter into account.;

Synthesis and characterization of polymorphs of photoluminescent Eu(III)-(2,5-furandicarboxylic acid, oxalic acid) MOFs

Science.gov (United States)

Shi, Fa-Nian; Ananias, Duarte; Yang, Ting-Hai; Rocha, João

2013-08-01

A novel metal organic framework (MOF) formulated as [Eu(H2O)2(fdc)(ox)0.5·(H2O)]n (1, fdc2-=2,5-furandicarboxylate, ox2-=oxalate), was hydrothermally synthesized via in situ ox2- generation from the partial decomposition of the fdc2- ligand. This material crystallizes in the monoclinic space group C2/c, unit cell parameters of 1: a=16.7570(10), b=10.5708(7), c=13.5348(14) Å, β=116.917(2)° (Z=8), and exhibits a three-dimensional (3D)-porous framework, with guest water molecules residing in the channel linking all other ligands (H2O, ox2-and fdc2-) via hydrogen bonding interactions. Compound 2 is a polymorph of 1 crystallizing in monoclinic P21/c space group. The photoluminescence properties of 1 and 2 were studied at room temperature. The spectra show the typical Eu3+ red emission and the differences observed reflects the slightly different structures of these polymorphs.

Tetraphenylphosphonium hydrogen oxalate

Directory of Open Access Journals (Sweden)

Philip A. W. Dean

2008-01-01

Full Text Available In the title compound, C24H20P+·C2HO4−, two symmetry-independent ion pairs are present. The cations aggregate into puckered sheets via zigzag infinite chains of sixfold phenyl embraces and parallel fourfold phenyl embraces, while the anions form hydrogen-bonded chains between the sheets of cations. In the two independent oxalate anions, the angles between the normals to the two least-squares carboxylate COO planes are unusually large, viz. 72.5 (1 and 82.1 (1°.

Formation and growth mechanism of TiC crystal in TiCp/Ti composites

Institute of Scientific and Technical Information of China (English)

金云学; 王宏伟; 曾松岩; 张二林

2002-01-01

Ti-C and Ti-Al-C alloys were prepared using gravity and directional solidification processes. Morphologies of TiC crystal were investigated by using SEM, XRD and EDX. Also, the formation and growth mechanism of TiC crystal have been analyzed on the basis of coordination polyhedron growth unit theory. During solidification of titanium alloys, the coordination polyhedron growth unit is TiC6. TiC6 growth units stack in a linking mode of edge to edge and form octahedral TiC crystal with {111} planes as present faces. Although the growing geometry of TiC crystal is decided by its lattice structure, the final morphology of TiC crystal depends on the effects of its growth environment. In solute concentration distribution, the super-saturation of C or TiC6 at the corners of octahedral TiC crystal is much higher than that of edges and faces of octahedral TiC crystal. At these corners the driving force for crystal growth is greater and the interface is instable which contribute to quick stacking rate of growth units at these corners and result in secondary dendrite arms along TiC crystallographic 〈100〉 directions. TiC crystal finally grows to be dendrites.

Crystal engineering of stable temozolomide cocrystals.

Science.gov (United States)

Babu, N Jagadeesh; Sanphui, Palash; Nangia, Ashwini

2012-10-01

The antitumor prodrug temozolomide (TMZ) decomposes in aqueous medium of pH≥7 but is relatively stable under acidic conditions. Pure TMZ is obtained as a white powder but turns pink and then brown, which is indicative of chemical degradation. Pharmaceutical cocrystals of TMZ were engineered with safe coformers such as oxalic acid, succinic acid, salicylic acid, d,l-malic acid, and d,l-tartaric acid, to stabilize the drug as a cocrystal. All cocrystals were characterized by powder X-ray diffraction (PXRD), single crystal X-ray diffraction, and FT-IR as well as FT-Raman spectroscopy. Temozolomide cocrystals with organic acids (pK(a) 2-6) were found to be more stable than the reference drug under physiological conditions. The half-life (T(1/2)) of TMZ-oxalic and TMZ-salicylic acid measured by UV/Vis spectroscopy in pH 7 buffer is two times longer than that of TMZ (3.5 h and 3.6 h vs. 1.7 h); TMZ-succinic acid, TMZ-tartaric acid, and TMZ-malic acid also exhibited a longer half-life (2.3, 2.5, and 2.8 h, respectively). Stability studies at 40 °C and 75 % relative humidity (ICH conditions) showed that hydrolytic degradation of temozolomide in the solid state started after one week, as determined by PXRD, whereas its cocrystals with succinic acid and oxalic acid were intact at 28 weeks, thus confirming the greater stability of cocrystals compared to the reference drug. The intrinsic dissolution rate (IDR) profile of TMZ-oxalic acid and TMZ-succinic acid cocrystals in buffer of pH 7 is comparable to that of temozolomide. Among the temozolomide cocrystals examined, those with succinic acid and oxalic acid exhibited both an improved stability and a comparable dissolution rate to the reference drug. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bubble formation upon crystallization of high nitrogen iron base alloys

International Nuclear Information System (INIS)

Svyazhin, A.G.; Sivka, E.; Skuza, Z.

2000-01-01

A study is made into the conditions of nitrogen bubble formation during crystallization of unalloyed iron, alloys of Fe-O, Fe-O-S systems, steels 1Kh13, 0Kh18N9 and a two-phase Fe-11%Cr-1%Mo-0.2%V steel. It is revealed that the amount of bubbles in a high nitrogen steel casting increases with a degree of nitrogen supersaturation and decreases with a cooling rate growth and with a rise of surfactant concentration in the metal. In sound castings a nitrogen content can be increased due to a cooling rate growth, nitrogen dilution with inert gas, an increase of nitrogen pressure during crystallization as well as due to the introduction of such surfactants as sulphur, selenium, tellurium, tin [ru

X-ray fluorescence analysis of ytterbium oxide/oxalate for rare earth impurities

International Nuclear Information System (INIS)

Chandola, L.C.; Khanna, P.P.; Thomas, A.

1982-01-01

An XRF method for the determination of Ho, Er, Tm, Lu and Y oxides in Yb 2 O 3 is described. 450 mg sample in the oxalate form is mixed with 150 mg boric acid binding material and pressed into 1.25 inch diameter pellet over a supporting pellet of boric acid. The sample is irradiated by X-rays from a tungsten tube and the fluorescent X-rays are dispersed by a LiF(200) crystal in a Philips PW 1220 semiautomatic X-ray fluorescence spectrometer. The intensities of characteristic X-rays of the impurity elements are measured by a flow proportional counter or a scintillation counter. The lowest determination limit is 0.005% for Ho, Er, Tm and Y and 0.01% for Lu. Calculations for theoretical detection limit, standard deviation and uncertainty are done and presented. (author)

Nutrition and oxalate metabolism in cats

NARCIS (Netherlands)

Dijcker, J.C.

2013-01-01

Over the past 30 years, a progressive increase in calcium oxalate (CaOx) urolith prevalence is reported in cats and dogs diagnosed with urolithiasis. This increase in prevalence appears to have occurred since dietary modifications were introduced to address magnesium ammonium phosphate urolithiasis.

Hydrazinium lanthanide oxalates: synthesis, structure and thermal reactivity of N2H5[Ln2(C2O4)4(N2H5)]·4H2O, Ln = Ce, Nd.

Science.gov (United States)

De Almeida, Lucie; Grandjean, Stéphane; Rivenet, Murielle; Patisson, Fabrice; Abraham, Francis

2014-03-28

New hydrazinium lanthanide oxalates N2H5[Ln2(C2O4)4(N2H5)]·4H2O, Ln = Ce (Ce-HyOx) and Nd (Nd-HyOx), were synthesized by hydrothermal reaction at 150 °C between lanthanide nitrate, oxalic acid and hydrazine solutions. The structure of the Nd compound was determined from single-crystal X-ray diffraction data, space group P2₁/c with a = 16.315(4), b = 12.127(3), c = 11.430(2) Å, β = 116.638(4)°, V = 2021.4(7) Å(3), Z = 4, and R1 = 0.0313 for 4231 independent reflections. Two distinct neodymium polyhedra are formed, NdO9 and NdO8N, an oxygen of one monodentate oxalate in the former being replaced by a nitrogen atom of a coordinated hydrazinium ion in the latter. The infrared absorption band at 1005 cm(-1) confirms the coordination of N2H5(+) to the metal. These polyhedra are connected through μ2 and μ3 oxalate ions to form an anionic three-dimensional neodymium-oxalate arrangement. A non-coordinated charge-compensating hydrazinium ion occupies, with water molecules, the resulting tunnels. The N-N stretching frequencies of the infrared spectra demonstrate the existence of the two types of hydrazine ions. Thermal reactivity of these hydrazinium oxalates and of the mixed isotypic Ce/Nd (CeNd-HyOx) oxalate were studied by using thermogravimetric and differential thermal analyses coupled with gas analyzers, and high temperature X-ray diffraction. Under air, fine particles of CeO2 and Ce(0.5)Nd(0.5)O(1.75) are formed at low temperature from Ce-HyOx and CeNd-HyOx, respectively, thanks to a decomposition/oxidation process. Under argon flow, dioxymonocyanamides Ln2O2CN2 are formed.

Formation of 1,2-diaminomaleicdinitrile crystals in radiolized solid hydrogen cyanide

International Nuclear Information System (INIS)

Mozhaev, P.S.; Kichigina, G.A.; Aliev, Z.G.; Kiryukhin, D.P.; Atovmyan, L.O.; Barkalov, I.M.

1994-01-01

A study was made on possibility of formation of 1,2-diaminomaleicdinitrile and mechanism of its occurrence in space environment. It was shown in experiments, that 1,2-diaminomaleicdinitrile crystals formed in solid HCN matrix, decomposed radiolytically at 77 K by 60 Co γ-rays with dose of 800 kGy during its sublimation T ≤ 260 K along with conjugated polymer of -C=N-C=N- type. It is shown that radiolysis of solid hydrocyanic acid results to formation of 1,2-diaminomaleicdinitrile with radiation yield G > 2. 11 refs., 1 fig., 1 tab

The tensile effect on crack formation in single crystal silicon irradiated by intense pulsed ion beam

Science.gov (United States)

Liang, Guoying; Shen, Jie; Zhang, Jie; Zhong, Haowen; Cui, Xiaojun; Yan, Sha; Zhang, Xiaofu; Yu, Xiao; Le, Xiaoyun

2017-10-01

Improving antifatigue performance of silicon substrate is very important for the development of semiconductor industry. The cracking behavior of silicon under intense pulsed ion beam irradiation was studied by numerical simulation in order to understand the mechanism of induced surface peeling observed by experimental means. Using molecular dynamics simulation based on Stillinger Weber potential, tensile effect on crack growth and propagation in single crystal silicon was investigated. Simulation results reveal that stress-strain curves of single crystal silicon at a constant strain rate can be divided into three stages, which are not similar to metal stress-strain curves; different tensile load velocities induce difference of single silicon crack formation speed; the layered stress results in crack formation in single crystal silicon. It is concluded that the crack growth and propagation is more sensitive to strain rate, tensile load velocity, stress distribution in single crystal silicon.

Characterization of calcium oxalate biominerals in Pereskia species (Cactaceae).

Science.gov (United States)

Monje, Paula V; Baran, Enrique J

2009-01-01

Calcium oxalate druses were isolated from the stems and leaves of six Pereskioideae family members and investigated by infrared spectroscopy, showing that in all samples the biomineral was present in the form of whewellite, CaC2O4 x H2O. As Pereskia is thought to represent the "ancestral" condition of the leafless stem-succulent cacti, these results suggest that the biomineralization of calcium oxalate in Cactaceae represents a primitive characteristic of the group and also support a close genetic relationship between Pereskia and Opuntia.

Complexation of Am(III) by oxalate in NaClO4 media

International Nuclear Information System (INIS)

Choppin, G.R.; Chen, J.F.

1995-01-01

The complexation of Am(III) by oxalate has been investigated in solutions of NaClO 4 up to 9.0 M ionic strength at 25 degrees C. The dissociation constants of oxalic acid were determined by potentiometric titration, while the stability constants of the Am(III)-oxalate complexation were measured by the solvent extraction technique. A thermodynamic model was constructed to predict the apparent equilibrium constants at different ionic strengths by applying the Pitzer equation using parameters for the Na + -HOx - , Na + -Ox - , AmOx + -ClO 4 - , and Na + -Am(Ox) 2 - interactions obtained by fitting the data

A new method for the analysis of soluble and insoluble oxalate in pulp and paper matrices

CSIR Research Space (South Africa)

Sithole, Bruce

2013-11-01

Full Text Available A novel method has been developed for determining soluble and insoluble forms of oxalate in pulp and paper samples by ion chromatography. Methanesulphonic acid is used to dissolve insoluble oxalate, and total oxalate is then determined by ion...

Calcium extraction from brine water and seawater using oxalic acid

Science.gov (United States)

Natasha, Nadia Chrisayu; Lalasari, Latifa Hanum

2017-01-01

Calcium can be extracted not only from rocks but also from natural liquor such as seawater and brine water. In order to extract the calcium from seawater and brine water, oxalic acid was used in this research. Effect of variations of the volume of the oxalic acid at a constant concentration in seawater and brine water to produce calcium was investigated. The concentration of oxalic acid was 100 g/l and the variations of its volume were 2 ml, 4 ml, 6 ml, 8 ml, 10 ml, 20 ml, 30 ml, 40 ml, and 50 ml. The used seawater and brine water were firstly evaporated from 100 ml into 50 ml and then the oxalic acid was added into them with mixing to produce the calcium precipitates. The precipitates were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM) and the filtrates were analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES). The SEM analysis showed that the precipitates from brine water were consisted of only calcium compound while from seawater sodium one was also found along with calcium compound. The XRD analysis showed that the calcium was present in the form of calcium oxalate for both seawater and brine water. The ICP-OES analysis of the filtrate from seawater precipitation showed that the its calcium content was decreased from 826.20 ppm to 0.04 ppm while from brine water, it decreased from 170.06 ppm to 1.96 ppm. These results showed that both seawater and brine water have the potential to be a raw material for calcium production.

Characterization of wheat germin (oxalate oxidase) expressed by Pichia pastoris

International Nuclear Information System (INIS)

Pan, Heng-Yen; Whittaker, Mei M.; Bouveret, Romaric; Berna, Anne; Bernier, Francois; Whittaker, James W.

2007-01-01

High-level secretory expression of wheat (Triticum aestivum) germin/oxalate oxidase was achieved in Pichia pastoris fermentation cultures as an α-mating factor signal peptide fusion, based on the native wheat cDNA coding sequence. The oxalate oxidase activity of the recombinant enzyme is substantially increased (7-fold) by treatment with sodium periodate, followed by ascorbate reduction. Using these methods, approximately 1 g (4 x 10 4 U) of purified, activated enzyme was obtained following eight days of induction of a high density Pichia fermentation culture, demonstrating suitability for large-scale production of oxalate oxidase for biotechnological applications. Characterization of the recombinant protein shows that it is glycosylated, with N-linked glycan attached at Asn47. For potential biomedical applications, a nonglycosylated (S49A) variant was also prepared which retains essentially full enzyme activity, but exhibits altered protein-protein interactions

EFFECTIVENESS OF USING DILUTE OXALIC ACID TO DISSOLVE HIGH LEVEL WASTE IRON BASED SLUDGE SIMULANT

International Nuclear Information System (INIS)

Ketusky, E

2008-01-01

At the Savannah River Site (SRS), near Aiken South Carolina, there is a crucial need to remove residual quantities of highly radioactive iron-based sludge from large select underground storage tanks (e.g., 19,000 liters of sludge per tank), in order to support tank closure. The use of oxalic acid is planned to dissolve the residual sludge, hence, helping in the removal. Based on rigorous testing, primarily using 4 and 8 wt% oxalic acid solutions, it was concluded that the more concentrated the acid, the greater the amount of residual sludge that would be dissolved; hence, a baseline technology on using 8 wt% oxalic acid was developed. In stark contrast to the baseline technology, reports from other industries suggest that the dissolution will most effectively occur at 1 wt% oxalic acid (i.e., maintaining the pH near 2). The driver for using less oxalic acid is that less (i.e., moles) would decrease the severity of the downstream impacts (i.e., required oxalate solids removal efforts). To determine the initial feasibility of using 1 wt% acid to dissolve > 90% of the sludge solids, about 19,000 liters of representative sludge was modeled using about 530,000 liters of 0 to 8 wt% oxalic acid solutions. With the chemical thermodynamic equilibrium based software results showing that 1 wt% oxalic acid could theoretically work, simulant dissolution testing was initiated. For the dissolution testing, existing simulant was obtained, and an approximate 20 liter test rig was built. Multiple batch dissolutions of both wet and air-dried simulant were performed. Overall, the testing showed that dilute oxalic acid dissolved a greater fraction of the stimulant and resulted in a significantly larger acid effectiveness (i.e., grams of sludge dissolved/mole of acid) than the baseline technology. With the potential effectiveness confirmed via simulant testing, additional testing, including radioactive sludge testing, is planned

Intercomparison of the measurements of oxalic acid in aerosols by gas chromatography and ion chromatography

Science.gov (United States)

Kawamura, Kimitaka; Barrie, Leonard A.; Toom-Sauntry, Desiree

2010-12-01

Oxalate, the anion of oxalic acid, is one of the most abundant measurable organic species in atmospheric aerosols. Traditionally, this bifunctional species has been measured by gas chromatography (GC) after derivatization to butyl ester and by ion chromatography (IC) without derivatization. However, there are few published comparisons of the two techniques. Here, we report the results of an intercomparison study for the measurement of oxalic acid in Arctic aerosols (oxalic acid by GC ranged from 6.5-59.1 ng m -3 (av. 26.0 ng m -3, median 26.2 ng m -3) whereas those by IC ranged from 6.6-52.1 ng m -3 (av. 26.6 ng m -3, median 25.4 ng m -3). They showed a good correlation ( r = 0.84) with a slope of 0.96. Thus, observations of oxalate obtained by GC employing dibutyl esters are almost equal to those by IC. Because the accuracy of oxalic acid by GC method largely depends on the method used, it is important to strictly examine the recovery in each study.

Syntheses, structures and properties of four 3D microporous lanthanide coordination polymers based on 3,5-pyrazoledicarboxylate and oxalate ligands

Science.gov (United States)

Song, Juan; Wang, Ji-Jiang; Hu, Huai-Ming; Wu, Qing-Ran; Xie, Juan; Dong, Fa-Xin; Yang, Meng-Lin; Xue, Gang-Lin

2014-04-01

Four three-dimensional lanthanide coordination polymers with reversible structural interconversions, [Ln2(Hpdc)2(C2O4)(H2O)4]n·2nH2O [Ln=Sm (1), Eu (2), Tb (3) and Dy (4)], have been synthesized by hydrothermal reactions of lanthanide nitrates with 3,5-pyrazoledicarboxylic (H3pdc) and oxalic acids. It is noteworthy that there is an in situ reaction in 1, in which H3pdc was decomposed into (ox)2- with Cu(II)-Sm(III) synergistic effect under hydrothermal conditions. These compounds are isostructural and crystallized in the monoclinic P21/c space group. The Ln(III) ions are eight-coordinated with dodecahedron coordination geometry. These polyhedra are linked by oxalate groups to form 1D zigzag chain, which are further connected by 3,5-pyrazoledicarboxylate to extend similar 3D frameworks with channels along c-axis in 1-4. These coordination polymers display the characteristic emission bands of the Ln(III) ions in the solid state and possess good thermal stabilities.

Comparison of the method of classes and the quadrature of moment for the modelling of neodymium oxalate precipitation

Energy Technology Data Exchange (ETDEWEB)

Gaillard, J.P.; Lalleman, S.; Bertrand, M. [CEA, Centre de Marcoule, Nuclear Energy Division, RadioChemistry and Process Department, F-30207 Bagnols sur Ceze (France); Plasari, E. [Ecole Nationale Superieure des Industries Chimiques, Laboratoire Reactions et Genie des Procedes, Universite de Lorraine - CNRS,1 rue Grandville, BP 20451, 54001, Nancy Cedex (France)

2016-07-01

Oxalic precipitation is generally used in the nuclear industry to deal with radioactive waste and recover the actinides from a multicomponent solution. To facilitate the development of experimental methods and data acquisitions, actinides are often simulated using lanthanides, gaining experience more easily. The purpose of this article is to compare the results achieved by two methods for solving the population balance during neodymium oxalate precipitation in a continuous MSMPR (Mixed Suspension Mixed Product Removal). The method of classes, also called discretized population balance, used in this study is based on the method of Litster. Whereas, the Quadrature Method of Moment (QMOM) is written in terms of the transport equations of the moments of the number density function. All the integrals are solved through a quadrature approximation thanks to the product-difference algorithm or the Chebyshev algorithm. Primary nucleation, crystal growth and agglomeration are taken into account. Agglomeration phenomena have been found to be represented by a loose agglomerates model. Thermodynamic effects are modeled by activity coefficients which are calculated using the Bromley model. The sizes of particles predicted by the two methods are in good agreement with experimental measurements. (authors)

Synthetic peptides derived from salivary proteins and the control of surface charge densities of dental surfaces improve the inhibition of dental calculus formation.

Science.gov (United States)

Grohe, Bernd

2017-08-01

Peptides descended from the salivary proteins statherin and histatin were recently identified in saliva and the acquired enamel pellicle (AEP), a proteomic layer coated on enamel. In particular, the statherin phosphopeptide DpSpSEEKFLR (DSS) was found to adsorb to enamel-like hydroxyapatite and inhibit plaque-related crystal formation. To determine the mechanism of these processes, we studied peptide-crystal interactions based on the sequences DSS and RKFHEKHHSHRGYR (RKF). The latter is a basic histatin sequence showing antimicrobial effects. To initiate crystallization we used calcium oxalate monohydrate (COM), a rather secondary phase in the oral environment, however highly amenable to experimental analyses of nucleation and growth processes. Using electron microscopy we found that the peptides DSS, DSS-RKF and DSS-DSS all inhibit crystal formation; with DSS-DSS showing the strongest effects while RKF showed no effect. In addition, using either enamel-like or mica substrates, we found that the ratio of the substrate's surface charge densities was directly correlated with the ratio of COM nucleation rates on theses surfaces. The findings suggest that mineralization processes on enamel/AEP-films are controllable by the degree of peptide phosphorylation/acidity and the level of the enamel surface charge density. Both parameters can, when well adjusted, help to overcome periodontal disease and dental calculus formation. In addition, the presence of antimicrobial RKF will reduce the buildup of bacterial plaque. Copyright © 2017 Elsevier B.V. All rights reserved.

Facile fabrication of cobalt oxalate nanostructures with superior specific capacitance and super-long cycling stability

Science.gov (United States)

Cheng, Guanhua; Si, Conghui; Zhang, Jie; Wang, Ying; Yang, Wanfeng; Dong, Chaoqun; Zhang, Zhonghua

2016-04-01

Transition metal oxalate materials have shown huge competitive advantages for applications in supercapacitors. Herein, nanostructured cobalt oxalate supported on cobalt foils has been facilely fabricated by anodization, and could directly serve as additive/binder-free electrodes for supercapacitors. The as-prepared cobalt oxalate electrodes present superior specific capacitance of 1269 F g-1 at the current density of 6 A g-1 in the galvanostatic charge/discharge test. Moreover, the retained capacitance is as high as 87.2% as the current density increases from 6 A g-1 to 30 A g-1. More importantly, the specific capacitance of cobalt oxalate retains 91.9% even after super-long cycling of 100,000 cycles. In addition, an asymmetric supercapacitor assembled with cobalt oxalate (positive electrode) and activated carbon (negative electrode) demonstrates excellent capacitive performance with high energy density and power density.

Formation of 1,2-diaminomaleodinitrile crystals in radiolyzed solid hydrocyanic acid

International Nuclear Information System (INIS)

Mozhaev, P.S.; Kichigina, G.A.; Aliev, Z.G.; Kiryukhin, D.P.; Atovmyan, L.O.; Barkalov, I.M.

1994-01-01

Hydrocyanic molecules, HCN, are widely found in various extraterrestrial objects and have come to be regarded as the building blocks of chemical evolution, because they convert directly to more complex organic compounds, such as amino acids, nucleotides, and proteins. While observing the low-temperature conversion of radiolyzed solid HCN, the authors noted the formation of an amorphous polymer and the nucleation and growth of needle shaped crystals. The crystals were studied by X-ray diffraction methods and believed to be formed by 1,2-diaminomaleodinitrile, a tetramer of HCN, arising by recombination of aminocyanocarbene diradicals. Cobalt 60 was used as the radiation source, preirradiating with a 800 kGy dose a solid HCN sample at 77K

Study on the Key Technology of High Purity Strontium Titanate Powder Synthesized from Oxalic Acid Co-sediment Precipitation

Science.gov (United States)

Bi, Xiaoguo; Dong, Yingnan; Li, Yingjie; Niu, Wei; Tang, Jian; Ding, Shuang; Li, Meiyang

2017-09-01

Oxalate coprecipitation is applied in this paper, high purity titanium tetrachloride, and after the purification of strontium chloride, match with a certain concentration of solution, oxalate and strontium chloride and titanium tetrachloride in 1.005:1.000 make strontium titanium mixture ratio, slowly under 60°C to join in oxalic acid solution, aging around 4 h, get oxygen titanium strontium oxalate (SrTiO(C2O4)2 • 4H2 ) precipitation, after washing, drying and other process made oxygen titanium strontium oxalate powder.

Comparison of Physicochemical Properties of Nano- and Microsized Crystals in the Urine of Calcium Oxalate Stone Patients and Control Subjects

Directory of Open Access Journals (Sweden)

Jie Gao

2014-01-01

Full Text Available Purpose. To compare the properties of different sizes of urinary crystallites between calcium oxalate (CaOx calculi patients and healthy controls. Methods. We studied the average particle size, size distribution, intensity-autocorrelation curve, zeta potential (ζ, conductivity, mobility, aggregation state, and stability of different sizes of urinary crystallites by nanoparticle size analysis and transmission electron microscopy after filtration through a microporous membrane with an aperture size from 0.22 μm to 0.45, 1.2, 3, and 10 μm. Results. The urinary crystallites of the CaOx calculi patients were uneven and much easy to aggregate than those of controls. The number of large-sized crystallites of the patients was significantly more than that of the controls. The main components of the nanosized urinary crystallites in patients were CaOx monohydrate (COM, uric acid, and β-calcium phosphate, and these components were basically similar to those of the microsized urinary crystallites. The urinary crystallites of the calculi patients were easier to aggregate than that of the controls, and the small-sized urinary crystallites were much easier to agglomerate. Conclusions. The urinary system of CaOx calculi patients is unstable and highly susceptible to urinary crystallite aggregation. The rapid aggregation of urinary crystallites may be the key factor affecting urolithiasis formation.

X-ray fluorescence analysis of erbium oxide/oxalate for rare earth impurities

International Nuclear Information System (INIS)

Chandola, L.C.; Khanna, P.P.; Thomas, A.

1981-01-01

A method for the determination of Tb, Dy, Ho, Tm, Yb, Lu and Y oxides in Er 2 O 3 is described. 450 mg sample in the oxalate form is mixed with 150 mg boric acid binding material and pressed into a 1.25 inch diameter pellet over a supporting pellet of boric acid. The sample is then irradiated by X-rays from a tungsten tube and the fluorescent X-rays are dispersed by a LiF (200) crystal in a Philips PW 1220 semiautomatic X-ray fluorescence spectrometer. The intensities of characteristic X-rays of the impurity elements are measured by a flow proportional counter for all elements except yttrium for which the intensities are measured by a scintillation counter. The lowest determination limit is 0.005% for all impurities except for Yb for which it is 0.01%. Calculations for theoretical detection limit are given. (author)

Liquid waste processing from plutonium (III) oxalate precipitation

International Nuclear Information System (INIS)

Esteban, A.; Cassaniti, P.; Orosco, E.H.

1990-01-01

Plutonium (III) oxalate filtrates contain about 0.2M oxalic acid, 0.09M ascorbic acid, 0.05M hydrazine, 1M nitric acid and 20-100 mg/l of plutonium. The developed treatment of liquid wastes consist in two main steps: a) Distillation to reduce up to 10% of the initial volume and refluxing to destroy organic material. Then, the treated solution is suitable to adjust the plutonium at the tetravalent state by addition of hydrogen peroxide and the nitric molarity up to 8.6M. b) Recovery and purification of plutonium by anion exchange using two columns in series containing Dowex 1-X4 resin. With the proposed process, it is possible to transform 38 litres of filtrates with 40mg/l of Pu into 0.1 l of purified solution with 15-20g/l of Pu. This solution is suitable to be recycled in the Pu (III) oxalate precipitation process. This process has several potential advantages over similar liquid waste treatments. These include: 1) It does not increase the liquid volume. 2) It consumes only few reagents. 3) The operations involved are simple, requiring limited handling and they are feasible to automatization. 4) The Pu recovery factor is about 99%. (Author) [es

Hydrothermal synthesis and characteristics of 3-D hydrated bismuth oxalate coordination polymers with open-channel structure

International Nuclear Information System (INIS)

Chen Xinxiang; Cao Yanning; Zhang Hanhui; Chen Yiping; Chen Xuehuan; Chai Xiaochuan

2008-01-01

Two new 3-D porous bismuth coordination polymers, (C 5 NH 6 ) 2 [Bi 2 (H 2 O) 2 (C 2 O 4 ) 4 ].2H 2 O 1 and (NH 4 )[Bi(C 2 O 4 ) 2 ].3H 2 O 2, have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic symmetry, P2 1 /c space group with a=10.378(2) A, b=17.285(3) A, c=16.563(5) A, α=90 deg., β=119.66(2) deg., γ=90 deg., V=2581.8(10) A 3 , Z=4, R 1 =0.0355 and wR 2 =0.0658 for unique 4713 reflections I >2σ(I). Compound 2 crystallizes in the tetragonal symmetry, I4 1 /amd space group with a=11.7026(17) A, b=11.7026(17) A, c=9.2233(18) A, α=90 deg., β=90 deg., γ=90 deg., V=1263.1(4) A 3 , Z=32, R 1 =0.0208 and wR 2 =0.0518 for unique 359 reflections I> 2σ(I). Compounds 1 and 2 are 3-D open-framework structures with a 6 6 uniform net, which consist of honeycomb-like layers connected to each other by oxalate units. While different guest molecules fill in their cavities of honeycomb-like layers, study of ultrasonic treatment on 2 indicates the replacement of NH 4 + by K + on potassium ion exchange. Thermogravimetric analysis indicates that the open-channel frameworks are thermally stable up to 200 deg. C, and other characterizations are also described by elemental analysis, IR and ultraviolet-visible diffuse reflectionintegral spectrum (UV-Vis DRIS). - Graphical abstract: Two novel 3-D extended porous coordination polymers have been synthesized by hydrothermal method. Both compounds are 3-D open-framework structures with a 6 6 uniform net, which consist of honeycomb-like layers connected to each other by oxalate units. While different guest molecules fill in their cavities of honeycomb-like layers. Study of ultrasonic treatment on 2 indicates the replacement of NH 4 + by K + on potassium ion exchange

Influence of chromium ions on the color center formation in crystals with garnet structure

International Nuclear Information System (INIS)

Ashurov, M.Kh.; Zharikov, E.V.; Laptev, V.V.

1985-01-01

The in fluence of chromium ions on the color center formation in crystals of yttrium-aluminium garnet, gadolinium-gallium garnet, gadolinium-scandium-gallium garnet, and yttrium-scandium-gallium garnet is studied. In addition to basic activator ions these crystals were coactivated also by chromium ions with two wide bands of fundamental absorption within the range of pump tube radiation with maximas close to 450 and 650 nm. The color centers for γ-irradiated samples were observed at 300 K by measuring the adsorption spectra within the 300-800 nm range. Temperature of destruction of the charge trapping sites was determined by the method of thermoluminescence measuring in the 100-500 K temperature range. Detection of recombination center luminescence was accomplished within the 200-1600 nm wavelength range. Chromium ions are found to hinder the formation of color centers as a result of γ-irradiation at room and higher temperatures within the wavelength range over 300 nm; i.e. Cr 3+ ions increase radiation resistance of all the investigated crystals

Formation of temperature fields in doped anisotropic crystals under spatially inhomogeneous light beams passing through them

Energy Technology Data Exchange (ETDEWEB)

Zaitseva, E. V.; Markelov, A. S.; Trushin, V. N., E-mail: trushin@phys.unn.ru; Chuprunov, E. V. [Nizhni Novgorod State University (Russian Federation)

2013-12-15

The features of formation of thermal fields in potassium dihydrophosphate crystal doped with potassium permanganate under a 532-nm laser beam passing through it have been investigated. Data on the influence of birefringence on the temperature distribution in an anisotropic crystal whose surface is illuminated by a spatially modulated light beam are presented.

Defect formation and magnetic properties of Co-doped GaN crystal and nanowire

International Nuclear Information System (INIS)

Shi, Li-Bin; Liu, Jing-Jing; Fei, Ying

2013-01-01

Theoretical calculation based on density functional theory (DFT) and generalized gradient approximation (GGA) has been carried out in studying defect formation and magnetic properties of Co doped GaN crystal and nanowire (NW). Co does not exhibit site preference in GaN crystal. However, Co occupies preferably surface sites in GaN NW. Transition level of the defect is also investigated in GaN crystal. We also find that Co Ga (S) in NW does not produce spin polarization and Co Ga (B) produces spontaneous spin polarization. Ferromagnetic (FM) and antiferromagnetic (AFM) couplings are analyzed by six different configurations. The results show that AFM coupling is more stable than FM coupling for Co doped GaN crystal. It is also found from Co doped GaN NW calculation that the system remains FM stability for majority of the configurations. Magnetic properties in Co doped GaN crystal can be mediated by N and Ga vacancies. The FM and AFM stability can be explained by Co 3d energy level coupling

Improving the two-step remediation process for CCA-treated wood. Part I, Evaluating oxalic acid extraction

Science.gov (United States)

Carol Clausen

2004-01-01

In this study, three possible improvements to a remediation process for chromated-copper-arsenate (CCA) treated wood were evaluated. The process involves two steps: oxalic acid extraction of wood fiber followed by bacterial culture with Bacillus licheniformis CC01. The three potential improvements to the oxalic acid extraction step were (1) reusing oxalic acid for...

The Relationship between Serum Oxalic Acid, Central Hemodynamic Parameters and Colonization by Oxalobacter formigenes in Hemodialysis Patients.

Science.gov (United States)

Gulhan, Baris; Turkmen, Kultigin; Aydin, Merve; Gunay, Murat; Cıkman, Aytekin; Kara, Murat

2015-06-01

Elevated pulse wave velocity (PWV) and central aortic blood pressures are independent predictors of increased cardiovascular morbidity and mortality in hemodialysis (HD) patients. Oxalic acid is a uremic retention molecule that is extensively studied in the pathogenesis of calcium oxalate stones. Oxalobacter formigenes, a member of the colon microbiota, has important roles in oxalate homeostasis. Data regarding the colonization by and the exact role of O. formigenes in the pathogenesis of oxalic acid metabolism in HD patients are scant. Hence, we aimed to determine the relationship between fecal O. formigenes colonization, serum oxalic acid and hemodynamic parameters in HD patients with regard to the colo-reno-cardiac axis. Fifty HD patients were enrolled in this study. PWV and central aortic systolic (cASBP) and diastolic blood pressures (cADBP) were measured with a Mobil-O-Graph (I.E.M. GmbH, Stolberg, Germany). Serum oxalic acid levels were assessed by ELISA, and fecal O. formigenes DNA levels were isolated and measured by real-time PCR. Isolation of fecal O. formigenes was found in only 2 HD patients. One of them had 113,609 copies/ml, the other one had 1,056 copies/ml. Serum oxalic acid levels were found to be positively correlated with PWV (r = 0.29, p = 0.03), cASBP (r = 0.33, p = 0.001) and cADBP (r = 0.42, p = 0.002) and negatively correlated with LDL (r = -0.30, p = 0.03). In multivariate linear regression analysis, PWV was independently predicted by oxalic acid, glucose and triglyceride. This is the first study that demonstrates the absence of O. formigenes as well as a relation between serum oxalic acid and cASBP, cADBP and PWV in HD patients. Replacement of O. formigenes with pre- and probiotics might decrease serum oxalic acid levels and improve cardiovascular outcomes in HD patients.

Effect of Ethylenediaminetetraacetic Acid and Ammonium Oxalate ...

African Journals Online (AJOL)

Effect of Ethylenediaminetetraacetic Acid and Ammonium Oxalate on the ... The test plant was sown in aluminium-polluted soil (conc. ... The perseverance of the test plant in the aluminium spiked soil is an indication of adaptation to the stress ...

Unsaturated glycerophospholipids mediate heme crystallization: biological implications for hemozoin formation in the kissing bug Rhodnius prolixus.

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Renata Stiebler

Full Text Available Hemozoin (Hz is a heme crystal produced by some blood-feeding organisms, as an efficient way to detoxify heme derived from hemoglobin digestion. In the triatomine insect Rhodnius prolixus, Hz is essentially produced by midgut extracellular phospholipid membranes known as perimicrovillar membranes (PMVM. Here, we investigated the role of commercial glycerophospholipids containing serine, choline and ethanolamine as headgroups and R. prolixus midgut lipids (RML in heme crystallization. All commercial unsaturated forms of phospholipids, as well as RML, mediated fast and efficient β-hematin formation by means of two kinetically distinct mechanisms: an early and fast component, followed by a late and slow one. The fastest reactions observed were induced by unsaturated forms of phosphatidylethanolamine (uPE and phosphatidylcholine (uPC, with half-lives of 0.04 and 0.7 minutes, respectively. β-hematin crystal morphologies were strikingly distinct among groups, with uPE producing homogeneous regular brick-shaped crystals. Interestingly, uPC-mediated reactions resulted in two morphologically distinct crystal populations: one less representative group of regular crystals, resembling those induced by uPE, and the other largely represented by crystals with numerous sharp edges and tapered ends. Heme crystallization reactions induced by RML were efficient, with a heme to β-hematin conversion rate higher than 70%, but clearly slower (t1/2 of 9.9-17.7 minutes than those induced by uPC and uPE. Interestingly, crystals produced by RML were homogeneous in shape and quite similar to those mediated by uPE. Thus, β-hematin formation can be rapidly and efficiently induced by unsaturated glycerophospholipids, particularly uPE and uPC, and may play a role on biological heme crystallization in R. prolixus midgut.

Hydrazinium lanthanide oxalates: synthesis, structure and thermal reactivity of N_2H_5[Ln_2(C_2O_4)_4(N_2H_5)].4H_2O, Ln = Ce, Nd

International Nuclear Information System (INIS)

De Almeida, Lucie; Grandjean, Stephane; Abraham, Francis; Rivenet, Murielle; Patisson, Fabrice

2014-01-01

New hydrazinium lanthanide oxalates N_2H_5[Ln_2(C_2O_4)_4(N_2H_5)].4H_2O, Ln = Ce (Ce-H_yO_x) and Nd (Nd- H_yO_x), were synthesized by hydrothermal reaction at 150 C between lanthanide nitrate, oxalic acid and hydrazine solutions. The structure of the Nd compound was determined from single-crystal X-ray diffraction data, space group P2_1/c with a = 16.315(4), b = 12.127(3), c = 11.430(2) Angstroms, β = 116.638(4) degrees, V = 2021.4(7) Angstroems"3, Z = 4, and R1 = 0.0313 for 4231 independent reflections. Two distinct neodymium polyhedra are formed, NdO_9 and NdO_8N, an oxygen of one monodentate oxalate in the former being replaced by a nitrogen atom of a coordinated hydrazinium ion in the latter. The infrared absorption band at 1005 cm"-"1 confirms the coordination of N_2H_5"+ to the metal. These polyhedra are connected through μ"2 and μ"3 oxalate ions to form an anionic three-dimensional neodymium-oxalate arrangement. A non-coordinated charge-compensating hydrazinium ion occupies, with water molecules, the resulting tunnels. The N-N stretching frequencies of the infrared spectra demonstrate the existence of the two types of hydrazine ions. Thermal reactivity of these hydrazinium oxalates and of the mixed isotypic Ce/Nd (CeNd-H_yO_x) oxalate were studied by using thermogravimetric and differential thermal analyses coupled with gas analyzers, and high temperature X-ray diffraction. Under air, fine particles of CeO_2 and Ce_0_._5Nd_0_._5O_1_._7_5 are formed at low temperature from Ce-H_yO_x and CeNd-H_yO_x, respectively, thanks to a decomposition/oxidation process. Under argon flow, dioxy-mono-cyanamides Ln_2O_2CN_2 are formed. (authors)

Catalytic upgrading of oleic acid into biofuel using Mo modified zeolite supported Ni oxalate catalyst functionalized with fluoride ion

International Nuclear Information System (INIS)

Ayodele, O.B.; Abbas, Hazzim F.; Daud, Wan Mohd Ashri Wan

2014-01-01

Highlights: • Modification of zeolite with freshly prepared molybdenum oxalate. • Functionalization of Ni oxalate with HF and incorporation into Mo modified zeolite. • Characterization of synthesized Mo modified zeolite supported Ni oxalate catalyst. • Deoxygenation of oleic acid with the synthesized zeolite supported catalyst. • Reusability study on the synthesized zeolite supported catalyst. - Abstract: In this study, fluoride ion functionalized nickel oxalate supported on molybdenum modified zeolite (NiMoFOx/Zeol) catalyst was synthesized, characterized and tested on the hydrodeoxygenation (HDO) of oleic acid (OA) into paraffinic fuel. The NiMoFOx/Zeol characterization results confirmed the presence of both Ni and Mo as well as the formation of NiMoO 4 which is a highly HDO reactive specie at 2θ value of 43.6° according to the XRD result. NiMoFOx/Zeol also showed loss in crystallinity and reduction in the average particle size leading to increase in the pore volume and specific surface area due to the combined effects of fluoride ion presence, oxalic acid functionalization and calcination. The effect of temperature, pressure and NiMoFOx/Zeol loading studied showed that initial increase in their values increased the yield of the target fractions until some points where reduction was observed. The best observed experimental conditions to hydrodeoxygenate 40 g (∼45 mL) of OA into 75% n-C 18 and 23% i-C 18 were 360 °C, 30 mg NiMoFOx/Zeol loading and 20 bar using 100 mL H 2 /min. The presence of i-C 18 was due to the functionalization of the catalyst with fluoride ion. The catalyst reusability result displayed excellent qualities with marginal loss of only 2% in activity after third reuse due to the improved synthesis protocol that employed organometallic precursor. The results are strongly encouraging for further studies toward industrialization of HDO process

Electron spectroscopy of the interface carbon layer formation on the cleavage surfaces of the layered semiconductor In4Se3 crystals

International Nuclear Information System (INIS)

Galiy, P.V.; Musyanovych, A.V.; Nenchuk, T.M.

2005-01-01

The results of the quantitative X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) of the interface carbon layer formation on the cleavage surfaces of the layered semiconductor In 4 Se 3 crystals are presented. The carbon coating formation occurs as the result of interaction of the air and residual gases atmosphere in ultra high vacuum (UHV) Auger spectrometer chamber with atomic clean interlayer cleavage surfaces of the crystals. The kinetics and peculiarities of interfacial carbon layer formation on the cleavage surfaces of the crystals, elemental and phase composition of the interface have been studied by quantitative XPS, AES and mass-spectroscopy

Kinetics and mechanism of photoaccelerated isotope exchange between U(VI) and U(IV) in oxalate solutions

International Nuclear Information System (INIS)

Shaban, I.S.; Owreit, M.F.; Nikitenko, S.I.

1992-01-01

A kinetic study of thermal and photoaccelerated U(IV)-U(VI) isotope exchange has been carried out in oxalate solutions at 11-40 deg C. The rate and quantum yield were determined as a function of U(IV), U(VI) and oxalate concentration, wavelength of incident light, temperature and absorbed dose of γ-radiation. The kinetic equations for thermal and photoaccelerated exchange have been obtained. It was assumed that the mechanism of exchange involves formation of U(V) as an intermediate, followed by slow exchange between U(V) and U(IV). The isokinetic dependence confirms the identity of limiting stages for thermal and photostimulated exchange. The upper component of photoexcited T 1 level of uranyl is supposed to be the most reactive in the process of U(V) generation. It was observed that the small doses of γ-radiation evoke the acceleration of isotope exchange, however, at D>100 krad the rate of exchange is reduced to the level of thermal exchange. (author) 8 refs.; 4 figs.; 2 tabs

Lattice Boltzmann Simulation of Kinetic Isotope Effect During Snow Crystal Formation

Science.gov (United States)

Lu, G.; Depaolo, D. J.; Kang, Q.; Zhang, D.

2007-12-01

The isotopic composition of precipitation, especially that of snow, plays a special role in the global hydrological cycle and in reconstruction of past climates using polar ice cores. The fractionation of the major water isotope species (HHO, HDO, HHO-18) during ice crystal formation is critical to understanding the global distribution of isotopes in precipitation. Ice crystal growth in clouds is traditionally treated with a spherically-symmetric steady state diffusion model, with semi-empirical modifications added to account for ventilation and for complex crystal morphology. Although it is known that crystal growth rate, which depends largely on the degree of vapor over- saturation, determines crystal morphology, there are no quantitative models that relate morphology to the vapor saturation factor. Since kinetic (vapor phase diffusion-controlled) isotopic fractionation also depends on growth rate, there should be direct relationships between vapor saturation, crystal morphology, and crystal isotopic composition. We use a 2D lattice Boltzmann model to simulate diffusion-controlled ice crystal growth from vapor- oversaturated air. In the model, crystals grow solely according to the diffusive fluxes just above the crystal surfaces, and hence crystal morphology arises from the initial and boundary conditions in the model and does not need to be specified a priori. Crystal growth patterns can be varied between random growth and deterministic growth (along the maximum concentration gradient for example). The input parameters needed are the isotope- dependent vapor deposition rate constant (k) and the water vapor diffusivity in air (D). The values of both k and D can be computed from kinetic theory, and there are also experimentally determined values of D. The deduced values of k are uncertain to the extent that the condensation coefficient for ice is uncertain. The ratio D/k is a length (order 1 micron) that determines the minimum scale of dendritic growth features

Photodegradation of 2-mercaptobenzothiazole in the γ-Fe2O3/oxalate suspension under UVA light irradiation

International Nuclear Information System (INIS)

Wang Xugang; Liu Chengshuai; Li Xiaomin; Li Fangbai; Zhou Shungui

2008-01-01

The aim of this study is to investigate the effect of various factors on the photodegradation of organic pollutants in natural environment with co-existence of iron oxides and oxalic acid. 2-Mercaptobenzothiazole (MBT) was selected as a model pollutant, while γ-Fe 2 O 3 was selected as iron oxide. The crystal structure and morphology of the prepared γ-Fe 2 O 3 was determined by X-ray diffractograms (XRD) and scanning electron microscopy (SEM), respectively. The specific surface area was 14.36 m 2 /g by Brunauer-Emmett-Teller (BET) method. The adsorption behavior of γ-Fe 2 O 3 was evaluated by Langmuir model. The effect of the dosage of iron oxide, initial concentration of oxalic acid (C ox 0 ), initial pH value, the light intensity and additional transition metal cations on MBT photodegradation was investigated in the γ-Fe 2 O 3 /oxalate suspension under UVA light irradiation. The optimal γ-Fe 2 O 3 dosage was 0.4 g/L and the optimal C ox 0 was 0.8 mM with the UVA light intensity of 1800 mW/cm 2 . And the optimal dosage of γ-Fe 2 O 3 and C ox 0 for MBT degradation also depended strongly on the light intensity. The optimal γ-Fe 2 O 3 dosage was 0.1, 0.25 and 0.4 g/L, and the optimal C ox 0 was 1.0, 0.8, and 0.8 mM with the light intensity of 600, 1200 and 1800 mW/cm 2 , respectively. The optimal initial pH value was at 3.0. The additional transition metal cations including Cu 2+ , Ni 2+ or Mn 2+ could significantly accelerate MBT degradation. This investigation will give a new insight to understanding the MBT photodegradation in natural environment